Sandbox for Proposed Challenges

Question

What is the Sandbox?

This "Sandbox" is a place where Code Golf users can get feedback on prospective challenges they wish to post to the main page. This is useful because writing a clear and fully specified challenge on your first try can be difficult, and there is a much better chance of your challenge being well received if you post it in the Sandbox first.

To post to the Sandbox, scroll to the bottom of this page and click "Answer This Question", or click on the "Add Proposal" link below. Click "OK" when it asks if you really want to add another answer. Write your challenge just as you would when actually posting it. You may also add some notes about specific things you would like to clarify before posting it. Other users will help you improve your challenge by rating and discussing it. When you think your challenge is ready for the public, go ahead and post it, and replace the post here with a link to the challenge and delete the Sandbox post.

To add an inline tag to a proposal use shortcut link syntax with a prefix: [tag:king-of-the-hill]

See the Sandbox FAQ for more information on how to use the Sandbox.

The Sandbox works best if you sort posts by "active".

Add Proposal

Search the Sandbox

• Most people include applicable tags in their proposal, so for instance you can search for all king-of-the-hill proposals by merely adding the tag name in quotes to the search query.

Browse your pending proposals

Get the Sandbox Viewer to view the sandbox more easily

Answer 1

Reverse Polish Notation-ing!

Your challenge is simply to write a function which converts a given arithmetical expression into it's Reverse Polish Notation form.

Input

Your function will be passed in an arithmetical expression, as a string, which may contain any of +-*/^() or a space. For example:

1+1 34 * 7^6 3 * (78 + 7)

Output

Your function should return the Reverse Polish Notation form of the input with a space between each number. The above inputs would output:

1 1 + 7 6 ^ 34 * 78 7 + 3 *

Scoring:

This is code-golf so shortest code wins. Bonuses are as follows:

• -15 for supporting brackets in the input (as in: ())
• -5 for supporting exponents (as in: ^)
• -10 for supporting floating point (decimal) numbers (formatted with a dot: 12.56)

You should support, at minimum, +, -, * and / operations.

Good luck!

---

To the sandbox:

• Should I give more examples or is 3 enough?
• Do you think the deductions are a fair amount off? Too much? Too little?
• Am I missing something really obvious? (I usually am!)

Answer 2

Print the Twelve Days of Christmas with twelve programming languages

Use twelve programming or scripting languages to write twelve programs, embedded within each other, to print the lyrics for Twelve Days of Christmas.

Each program will write the next program to file, compile if needed, and execute it. The parent processes will not exit until the last has executed. When they exit, they will print the final verse, program by program. You may only have one file to start with. You may also, optionally, have a text file with each line of the song in it.

You must specifiy any dependencies needed to run the programs. For example, if you need a compiler, such as GCC, or PHP or the Java compiler/Java, put them in a list of dependencies.

For example:

<?php
echo "On the first day of Christmas, my true love gave to me:\nA partridge in a pear tree!\n";
$code = <<<EOD
public static void main(String [ ] args) {

String nextCode = new String;
System.out.println("On the second day of Christmas, my true love sent to me:");
System.out.print("Two Turtle Doves\nand a Partridge in a Pear Tree\n");
nextCode = "(Next code to be written is in here)";
PrintWriter writer = new PrintWriter("thirdDay.c", "UTF-8");
/*
* and write the next program, in this case, thirdDay.c to file and so on....
*/
}
EOD;
file_put_contents("secondDay.java", $code);
exec("javac secondDay.java");
echo exec("java secondDay");
echo "and a Partridge in a pear tree"; // runs after the other twelve have run
?>

Apologies for my rusty Java.

To reiterate:

1. The program is started
2. The program prints the appropriate verse
3. The program writes the source code for the next program to file, which in turn contains the code for the rest, and so on.
4. The program compiles (if needed) the next program, and runs it.

The final program will only print the line for Day 12. It will then exit, returning to its parent program, which will print the second line - Day 11, exit, and so on. In my example, this line will run last:

echo "and a Partridge in a pear tree"; // runs after the other twelve have run

Have fun with those quote marks. I started with PHP and Heredoc for a reason ;)

Assume that this will be run in a Linux/Unix terminal. Windows is okay if you can pull it off.

This is a popularity contest. Assuming that you can get everything escaped properly ;)

Merry Christmas!

Answer 3

A natural divisor

Expressiveness, natural language elements and readability, these are just a few of the awesome features/ideologies modern high-level languages promise us. But how "readable" and "natural" are these languages really? Can you really read them as they were english? In this challenge you have to prove how (un)natural your preferred language really is.

Challenge

You're to write a program that accepts a list/string of numbers from the STDIN, and outputs their greatest common divisor to the STDOUT. However you also need to write a complete description of your program, an english explanation of your entire program. The challenge is to make your program resemble the description as much as possible. As in a perfect natural programming language there would be no difference, your score will be the Levenshtein distance between your program and your description.

Rules

• Your description can only contain correct english sentences. The sentences must be at least six words long.
• The description must contain the full and correct process of your program. Nothing more or less. An example can be found below. As a general rule: a programmer that doesn't understand your language should completely understand your description and should be able to recreate the exact algorithm.
• Your program cannot contain both comments or strings.
• Your program should use the universal accepted definition to calculate the greatest common divisor. If the input only contains 0's, you have to output 0.

Example

This is a fibonacci function to illustrate how a description should look like:

PROGRAM:
def F(n):
    if n == 0: return 0
    elif n == 1: return 1
    else: return F(n-1)+F(n-2)

DESCRIPTION:
Define a function F with input n. If n equals 0, return 0. 
Else, if n equals 1, return 1. 
Else, return the output of F with input n minus 1, 
plus the output of F with input n minus 2.

Score

As mentioned earlier, your score is the levenshtein distance between your description and your program. You can calculate your levenshtein distance with the following snippet (thanks doorknob):

var f=document.getElementById("f"),g=document.getElementById("s"); function h(){var a=f.value,e=g.value;if(128<a.length)a="<span style='color:red'>First program is too long!</span>";else if(128<e.length)a="<span style='color:red'>Second program is too long!</span>";else{if(0===a.length)a=e.length;else if(0===e.length)a=a.length;else{var d=[],b;for(b=0;b<=e.length;b++)d[b]=[b];var c;for(c=0;c<=a.length;c++)d[0][c]=c;for(b=1;b<=e.length;b++)for(c=1;c<=a.length;c++)d[b][c]=e.charAt(b-1)===a.charAt(c-1)?d[b-1][c-1]:Math.min(d[b-1][c-1]+1,Math.min(d[b][c-1]+1,d[b-1][c]+ 1));a=d[e.length][a.length]}a="Distance = <strong>"+a+"</strong>"}document.getElementById("d").innerHTML=a}f.onkeyup=h;g.onkeyup=h;

<h3 id=ft>program</h3>
<textarea id=f rows=7 cols=80 style="width:100%"></textarea>
<h3 id=st>description</h3>
<textarea id=s rows=7 cols=80 style="width:100%"></textarea>
<p id=d></p>

Sandbox questions/notes:

• The question was just crazy idea for the most part. Do you think this question would work?
• Are there any languages that would get an unfair advantage? Are there more things I should ban?
• I know the description of the program description is somewhat subjective, so the answers would mostly involve being creative with their description. Are their any additional rules that could restrain this?

Answer 4

Final Exam Grade Calculator

So, it's around time for finals, and many students want to know what grade they need on their final exam to achieve an A, B, or sometimes a passing grade. There are many factors here - the weight of the final, two quarters having weight, what grade the students want - but it is still a simple task.

Objective

Write a program that will take three integers and output the grade they need to receive on the final.

Input

Three integers. The first two will be from 0 to 100, and the last will be from 1 to 100. They represent the current score in the class, the desired score, and the weight of the final, respectively. A working example can be found here.

Any input outside the expected ranges can have undefined behavior.

Output

The score the student needs to receive on the final exam. This score could be above 100 (every once in a while, students have unrealistic expectations), but if it is a negative number, it is automatically 0. The formula for score is as follows.

(desired - (current score * (1 - weight*.01))) * 100/weight

The output may not be an integer. In this case, round to the nearest hundredth (round up for .##5).

Examples

Input: 100 90 20    
50

Input: 65 60 30
48.33

Input: 54 100 25
238

Scoring

This is a code-golf challenge, so the shortest code wins.

Bonuses

• -10% if your code can take either 3 or 4 integers as input. If four integers are taken, then the first two are averaged to give what would normally be the first integer. Each of the first two integers here represents a quarter grade.

What other bonuses should I add? I can't think of many right now, but even one or two more would be helpful.

Answer 5

Possible resistances from resistors

code-golf electrical-engineering

Meta: Note this is far from done; just putting this idea out so that I can continue working on it. IE way work in progress. I need to specify a lot more of this and I'm putting this here because I know I won't end up working on this if it isn't here.

Given a set of resistors, output all the possible resistances that can be formed with them.

Thoughts so far:

Input:

Input will be a comma-separated or space-separated list of natural numbers such as

1 4 3 2 4 3 5 999

Output:

Output will be all the possible formable resistances, sorted, on its own lines, plus the number of ways to form each resistance.

(no example yet)

Answer 6

Implement the Henkin quantifier

code-golf logic

Your goal is to implement the Henkin quantifier Q_H, a generalized (branching) quantifier on four variables x1,x2,y1,y2 and a Boolean function f. It expresses the idea that for every choice of the x's, there's a choice of the y's so that the four variables satisfy f, so that each y depends only on the corresponding x and not the other one.

The parallelness of the choice of is sometimes represented by stacking the paired quantifiers like this:

This quantfier cannot be expressed in first-order logic.

The parallel choices for the y's are like prisoners being interrogated in separated rooms. They are each asked the respective questions x1 or x2 and must give respective answers y1 and y2 without knowing what the other one was asked, so they are liable to be trapped in inconsistent claims. The guards then evaluate the validity of their responses ointly by some function f that depends on both questions and answers. If the prisoners can always win this game, then f satisfied the Henkin quantifer Q_H.

Formally, the Henkin quantifier Q_H takes in a Boolean function f of four inputs (x1,x2,y1,y2), and evaluates whether the following statement is True:

For every x1 there exists a y1, and for every x2 there exists a y2, so that f(x1,x2,y1,y2) is True, and the choice of y1 depends only on x1 and the choice of y2 depends only on x2.

Alternatively stated in Skolem normal form

There exists functions g1 and g2 so that for every x1 and x2, the function f(x1,x2,g1(x1),g2(x2)) is True.

For this challenge, the domain of discourse will be natural numbers from 0 to 9.

Input:

A function f that takes in four numbers x1,x2,y1,y2, each between 0 and 9 and produces a Boolean output.

Output:

A consistent Truthy value if f satisfies the Henkin quantifier Q_H, and a Falsey value if it does not.

---

Questions for Sandbox:

1. Does this challenge make any sense?

2. What should the input format be? Not every language can take in functions. What about nested lists? Subsets of four-digit numbers?

Answer 7

The Great, White, North! code-golf - POSTED

Answer 8

Solve a LaserTank level (optimally?) [WIP]

LazerTank is more than just a computer game, it is a blast from the past. In this game, the player controls a tank that shoots lasers and navigates through a series of puzzles. The goal of this challenge is to write a program that solve game levels.

TODO: Actually explain how LaserTank works. There is an instructions page on the website.

Input will be an ASCII representation of the game map. TODO: determine which characters stand for what stuff.

Output will be the list of actions required. There are four possible actions for each step in the solution, "move forward," "turn left," "turn right," and "shoot".

Answer 9

Counting k-mers

The task is to count the number of distinct substrings of length k, for k = 1,2,3,4,.....

score

Your score is the highest k you can get to on my computer in under 1 minute.

You should use http://hgdownload.cse.ucsc.edu/goldenPath/hg38/chromosomes/chr2.fa.gz as your input and ignore new lines.

You should ignore all newlines. You can preprocess the input to decompress it before starting.

The following code outputs a histogram of all the 4-mers. You can then count how many there are with wc.

awk -v substr_length=4 '(len=length($0))>=substr_length{for (i=1; (i-substr_length)<len; i++) substrs[substr($0,i,substr_length)]++}; END{for (i in substrs) print substrs[i], i}' file.txt

(This question is not finished yet.)

fastest-code

Answer 10

Elevator Control [WIP]

The controller is still a WIP, but I have a decent idea of how it'll work.

You have been hired as a Vertical Integration Specialist (programmer) at Ascension Incorporated to write advanced elevator controller software. (backstory wip)

Elevators are Cool

The current setup is that there will be ten floors and three elevators. This is 100% subject to change. I'm not exactly sure how the game will be judged, below is an idea.

As people begin queue up, your elevators will be responsible for making sure that they get where they want to go. Each game tick, there is a certain % chance that a person will queue up at a given floor with a random destination. You goal is to transport 1000 people in the least time possible.

Details

Your submission will be the the form of a Java class. This class must contain at least two methods: the constructor mySubmission(Elevator[] elevators, Floor[] floors) and update(Elevator[] elevators, Floor[] floors). The constructor class will be called once, and update after every game tick.

Elevator Class:

• int location gives the current floor location of the elevator. (Read-only)
• int dest gives the destination of the elevator. All elevators have a destination, even an idle elevator, in which case the destination is the current floor. (readOnly)
• String status is idle or busy. Elevators which are idle are not moving and have no floors in queue. (read-only)
• boolean[] buttons tells which buttons have been pushed, signifying that a person in the elevator wants to go to that floor.
• ArrayList<Integer> destQueue gives the list of destinations for this elevator. An idle elevator with something in destQueue will become busy and have a new destination. (writable)
• goToFloor(int i) adds that floor to the queue if it is not already in it.
• clearQueue() clears the queue. Simple as that.

Floor Class

• boolean waiting means that somebody is at that floor.
• boolean up means that somebody on that floor wants to go up.
• boolean down means that somebody on that floor wants to do down.

Answer 11

Random distribution in array with exact number of occurences and max size

Write a program or a function, that takes 3 inputs x y z, where :

x is an integer representing the max size of each output array.
y is an integer representing the exact number of occurence of each z value.
z is a set of n integers to distribute

and outputs a set of arrays containing z values randomly distributed (each array must be unique, different ordered array are not the same).

Rules

• Each value of z can only appear once in each output array
• x value is between 2 and 10
• y value is between 1 and 10
• n is between 2 and 50
• z's n values are between 0 and 50
• If and only if n * y isn't divisible by x you can output one array with less than x elements
• "Random" means that every possible output must be produced with finite probability (barring the finite length of the PRNG's cycle)
• You can assume valid inputs, and there will always be at least 1 possible solution

Example

Input :

4 5 [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19]

Output :

[[3 18 16 10][9 0 2 11][6 12 0 9][15 16 10 4][4 17 16 14][14 3 15 2][5 4 7 16][17 5 0 13][13 11 7 6][2 9 8 12][5 13 7 2][7 1 8 14][11 19 17 0][17 19 6 13][3 1 5 15][15 18 0 7][19 14 18 10][1 16 10 9][1 12 14 10][9 15 4 12][8 4 3 5][19 11 18 3][13 12 17 11][6 1 8 19][18 8 2 6]]

Input

4 5 [0 1 2 3 4]

Output

[[0 3 2 1][0 3 2 4][3 2 1 4][2 0 1 3][1 0 3 4][4 2 0 1][4]]

Winning Criterion

This is code-golf so the shortest answer wins.

Note

This is actually based on SO question that I asked, and you can find a Java implementation here : https://stackoverflow.com/questions/28544808/random-distribution-of-items-in-list-with-exact-number-of-occurences

Sandbox

Definition of random : Should I accept output that contain same "subset" array ordered differently? Output format : How can I better define the output expected?

Answer 12

Can you reach this chess position?

This is currently a stub. If it makes sense I will write it out.

You should write a program which given a chess position outputs a list of moves (white and black alternating) with which the given position can be reached from the standard starting position. Your goal is to minimize the number of moves.

Input details:

will be in following the format (but of course not the staring position):

rnbqkbnr
pppppppp
........
........
........
........
PPPPPPPP
RNBQKBNR

• Inputs will be chosen from random positions of random low-level games (~1200 Elo).
• You only have to reach the given position with legal moves. You don't have to care if any castling or en-passant was available in the input.
• You can choose whose turn it is.

Output details:

• Is a list of [a-f][1-8] [a-f][1-8][qrbn]? ([qrbn]? is for promotion, if there is a standard notation for it, that will be used).

Other details:

• Running time of your program should not take more than one minute on your computer.
• Program shouldn't be longer than 50Kb. (this is against hardcoding databases thought that might wouldn't help that much)
• Standard loopholes are disallowed.

Scoring:

• Sum of the moves (half-moves) for the 20 provided inputs. If hardcoding happens those are subject to change. If a program can't reach a given input in 1 minute it's score is 300 for that testcase.

Sandbox notes:

A validator would be useful. I can't do a JS snippet but maybe I can hack together a python3 one.

(You don't have to implement castling, en-passant, promotion if you don't want to and still can get a great entry.)

Answer 13

Find the Point of Maximum Light

Inspired by this program, this challenge is about finding the point where the mouse should be placed, given an input in a form which will be specified later, in order to color the most pixels yellow.

The above link will bring you to a program with a hexagon, a triangle, and a line. When the mouse is moved over the shapes, light rays shine from the mouse and the various shapes absorb the light.

Input is given in this format: [250,200,150,100 250,200,300,120 150,100,300,120] [250,350,350,250] (Compare to the lines array in the aforementioned program). Your program is to assume the perimeter ([0,0,400,0 0,0,0,400 400,0,400,400 0,400,400,400]) is always present.

This is code-golf, so the shortest code wins.

NOTE: please tell me if I can clarify my question.

Answer 14

Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo

I'm not sure how or if this can even work in any language, but I figured I'd toss the idea up here for someone else to flesh out in case it's actually viable.

"Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo" is a grammatically correct American English sentence. This is possible because there are three different meanings of the word "buffalo" (or "Buffalo") used in the sentence, and some other words and punctuation are implied rather than explicitly included.

I think this would be a great code challenge to issue, if it is at all possible. It may not be proper for code-golf, but that would put an interesting spin on it as well.

The objective would be to create a script or program which is made up only of a single command, or sequence of commands, which is identically repeated throughout the source. No other code is permitted to fill or wrap the repeated piece. Within the script or program, those commands must do something in at least three different ways (or do three totally different somethings) despite being written exactly the same (perhaps with some allowance for deviations in capitalization, such as in the actual sentence) for every iteration.

A fictitious (and obviously invalid) PowerShell example is below.

Code:

echo 'buffalo';echo 'buffalo';echo 'buffalo';

Output

buffalo
Buffalo
BUFFALO

(Note: The Output could be easily achieved by simply modifying the capitalization of "buffalo" within the script, but that would be in violation of the spirit of the challenge - such deviations, if permitted at all, should not be allowed in string literals.)

Answer 15

Regex vs HTML

---

As the Stack Overflowers have been defeated, it is up to the Programming Puzzlers and Code Golfers to fight this final battle against the regex-resisting HTML-hordes. Pick up your flavour of choice and join the melee, with the shortest regex you can achieve (no, not like this)!

Challenge

Write a regex which takes a html tag, and splits it into tag name, attributes and body. For example, <img src="something.jpg">caption</img> is converted to img, src="something.jpg" and caption. Your regex will be run by the controller against a list of tests. Any regex flavour can be used, as long as there is a driver available (or you want to write your own).

Rules

• The regex should contain at least 4 groups, one each for tag name, tag attributes, tag body (contents) and a group for the html tag matched, which may be group 0 (which will not add to your regex length).
• Your regex does not need to handle all the test cases, but the more handled, the higher your score.
• The scoring formula is (100 - log(self.length) * 40) * ((passes - total) / total + 1), but this will be handled by the scoring program. This formula might change, based on how the challenge progresses. A higher score is better.
• For your regex, you must specify the driver you use (the name in square brackets), any flags and the group names or numbers that hold the split bits. Flags do not contribute towards regex length.

Testing

• Your program will be run over 30 tests (more may be added) by the scoring program, and the number of passes counted.
• Length is in bytes.
• Your score then is (100 - log(length) * 40) * ((passes - total) / total + 1), but this will be handled by the scoring program. This formula might change, based on how the challenge progresses.

• Types of html that you can score points on (remember not all need to be handled):

  • Paired html tags - <a>b</a>
  • Tags with the self-closing syntax - <br/>
  • Quoted attributes (using either single or double quotes) - <a href='mysite.com'>b</a>
  • Unquoted attributes - <b strength=1>msg</b>
  • Empty or boolean attributes - <input disabled/>
  • Comments (tag name is !--, attrs is empty, body is the text of the comment) - <!-- Something important -->
  • DOCTYPE sections (tag name is !DOCTYPE, body is the following text) - <!DOCTYPE html>
  • CDATA sections (tags inside ignored) - <![CDATA[<br/>]]>

• Example tests (one on each line, full list of tests and answers):

  <a>b</a>
  <a href='mysite.com'>b</a>
  <a href='mysite.com' color="blue" height=1>b</a>
  <quote href="http://somewhere.com">"he said this"</quote>
  <div class="quote">The answer is <div id='the-answer'>42</div></div>
  f'g(<b>x</b>)g'(<b>y</b>)
  <input text='Your name:' focused/>
  

• Answers to examples (one on each line):

  Name   Attrs                                    Body                                         Matched
  =================================================================================================================================================================
  a                                               b                                            <a>b</a>
  a      href='mysite.com'                        b                                            <a href='mysite.com'>b</a>
  a      href='mysite.com' color="blue" height=1  b                                            <a href='mysite.com' color="blue" height=1>b</a>
  quote  href="http://somewhere.com"              "he said this"                               <quote href="http://somewhere.com">"he said this"</quote>
  div    class="quote"                            The answer is <div id='the-answer'>42</div>  <div class="quote">The answer is <div id='the-answer'>42</div></div>
  b                                               x                                            <b>x</b>
  input  text='Your name:' focused                                                             <input text='Your name:' focused/>
  

• There is a timeout for the regex matching (currently 5 seconds, but this may change depending on the number of submissions), so if you are making a bit / computationally expensive regex, use a fast driver. The tests will be run on a 2013 MacBook Air, most likely single threaded (although 4 cores are available).

Drivers

Contributions of drivers is much appreciated. See the instructions on github.com.

Results

Name                          Length    Score     Passes    Fails     Timeouts  Errors    
==========================================================================================
Naive                         68        10.6799   12        18        0         0         

Tags: code-golfregular-expressionparsing

---

Sandbox Questions

• Is the scoring formula fair?
• Is this too easy / hard?
• Would abstracting the controller a bit more allow the controller and drivers be useful for scoring other challenges? Would anybody want to use it?
• There is currently a python and a perl driver. Are there any other major regex flavours that should be supported, or should I wait and see until after the sandbox?
• Is there any parts of the challenge that are a bit clunky and need rewriting?
• Could someone add this to the listing at the top?
• Anything I've missed?

Answer 16

Make a Space Heater

I've been out shoveling snow all day, and my hands are freezing! Heat them up with my computer.

Here's an (ungolfed) Linux C solution:

#include <stdlib.h>
#include <stdbool.h>
#include <unistd.h>
#include <sys/prctl.h>
#include <sys/wait.h>
#include <sys/sysinfo.h>

int main() {
    int cpu_cores = get_nprocs_conf();

    for (int i = 0; i < cpu_cores; i++) {
        if (fork() == 0) {
            nice(19);
            while (true);
        }
    }
    while (wait(NULL) > 0);
    return 0;
}

Additional Rules:

1. It must use all my CPU cores! More cores means more heat. (Processes are not required. You can use threads, or whatever. Just keep my cores pegged.)
2. Don't slow down my system. I might want to watch cat videos while my hands are warming. (The example does this with nice)
3. Shortest answer in bytes wins.

Answer 17

Navigate My Time Machine

challenge-type-undecided

This is a pretty broad idea, but time travel is a lot cooler than space travel. The basic idea is that the program will have to sort out the path of various objects through time, given certain constraints as to what must be where, when.

There are a few different models of time machine that could be used, based upon which type of time travel we want to use.

One possible example is the time travel model used in the film Primer. Notably, the machine must be turned on before it can be used. I find this model to be fairly "realistic," if that term can be used in regards to time travel.

There would also be the requirement of conservation of mass. If there there are multiple copies of an object, then "the number of forward-moving copies" - "the number of backwards-moving copies" = 1. The most important point is that there is a single "unified" timeline.

One idea is to create a long list of various objects, listing the known sightings of each one. From this list of information, the program must sort out the path of each object through time, ensuring that each duplicate object is accounted for and that conservation of mass is obeyed.

Additional ideas include determining how much additional aging each object has experienced as a result of the time travel.

Answer 18

Design Logic Circuits with CSWAP Gates

A universal logic gate is a logic gate is one that is capable of creating any other logic gate or circuit. For example, it is possible to wire together dozens of NAND gates to form any logic circuit you so desire.

Beyond a universal gate, a reversible logic gate is one whose (multiple) outputs can be used to determine the input. One notable reversible universal gate is the Fredkin Gate, also known as the CSWAP gate. This gate has three inputs and three outputs, yet is very simple. CSWAP stands for "controlled swap" and describes exactly what the gate does. If the first input is a 0, the three outputs are the same as the three inputs. If the first input is a 1, the second and third outputs are swapped.

Here is the ever-so-important truth table.

in  | out
----+----
000 | 000
001 | 001
010 | 010
011 | 011
100 | 100
101 | 110
110 | 101
111 | 111

The Challenge

You goal is to write a program that takes a truth table as input and constructs a logic circuit to match it. (other ideas are taking a non-CSWAP circuit as input and converting it to CSWAP).

Here are the rules of circuit design:

• A circuit has a certain number of inputs and outputs, the quantities of which will be given.
• You have an unlimited supply of CWAP gates with which to construct circuits.
• You also have an unlimited supply of constants (a source that always takes on the assigned value) and trash bins (a place to send an unneeded bit).
• Each data source (circuit input / gate output / constant) must be linked via wire to exactly one data sink (circuit output / gate input / trash bin), and vice-versa.
• Possible extra rule: no loops in the circuit.

ASCII representation

Using ASCII to draw the circuits may be unnecessary, but here is how it could be done.

• Wires are - and |, which connect the two horizontally or vertically adjacent cells.

• Inputs are capital letters, while outputs are lowercase letters. Constants are 1s and 0s. Trash bins are #.

• CSWAP gates are formed by OXX in any of the four basic orientations. The O is the control, while XX are the two inputs/outputs to be swapped. I might need to adjust this so that adjacent gates with multiple orientations are unambiguous.

AND gate

A-O-#
B-X-#
0-X-a

NOT gate

A-O-#
0-X-#
1-X-a

(more details coming sometime not now)

Answer 19

Game Of Riches

---

This is a programming challenge based off the game AdVenture Capitalist.

Goal Of The Game

---

The goal is to have the most angel investors after 1 month (2,592,000 seconds) of gameplay.

Angel Investors

---

Angel Investors are the primary way to increase your profit in the long run. Angel Investors can be sacrificed for Angel Upgrades. Angel Investors also increase your profit by ANGEL_EFFECTIVENESS% each. For example, 20 angel investors increase your profit by 40%. You earn Angel Investors in proportion to the square root of your life earnings. The catch is that Angel Investors can only be used after a reset.

ANGEL_EFFECTIVENESS is 2 by default. It can be increased by unlocks and upgrades.

Angel Investors are earned according to this formula: 150 * sqrt(LIFETIME_EARNINGS / 1e15)

Money

---

You earn money through the use of businesses. Money is used to purchase businesses and upgrades. The more money you have earned in your lifetime (since your program started execution), the more angels flock to your cause.

Businesses

---

Businesses can earn you money. There are 10 types of businesses. The price of a business increases exponentially. You can also earn unlocks by achieving certain numbers of businesses. You start with 1 lemonade stand.

Name               |    Base Price   |  Base Profit / second  | Price Increase per Purchase
-------------------------------------------------------------------------------------------
LEMONADE_STAND     |              $4 |                  $1.66 | 7%
NEWSPAPER_DELIVERY |             $60 |                    $20 | 15%
CAR_WASH           |            $720 |                    $90 | 14%
PIZZA_DELIVERY     |          $8,640 |                   $360 | 13%
DONUT_SHOP         |        $103,680 |                 $2,160 | 12%
SHRIMP_BOAT        |      $1,244,160 |                 $6,480 | 11%
HOCKEY_TEAM        |     $14,929,920 |                $19,440 | 10%
MOVIE_STUDIO       |    $179,159,040 |                $58,320 | 9%
BANK               |  $2,149,908,480 |               $174,960 | 8%
OIL_COMPANY        | $25,798,901,760 |               $804,816 | 7%

Unlocks

---

Unlocks are bonuses that are earned when a set goal has been achieved.

Example list (not actual):

LEMONADE_STAND;25;LEMONADE_STAND;PROFIT;2
NEWSPAPER_STAND;900;OIL_COMPANY;PROFIT;11
ALL;2222;ALL;PROFIT;2

Upgrades

---

Upgrades are bonuses that are purchased with money or angels. See Angel Upgrades for details on upgrades that are purchased with angels.

Example list (not actual):

0;CASH;2.5e5;LEMONADE_STAND;PROFIT;3
1;CASH;500000;NEWSPAPER_DELIVERY;PROFIT;3
2;CASH;1e21;ANGEL;EFFECTIVENESS;1

Angel Upgrades

---

Angel Upgrades are bonuses that are purchased with the sacrifice of angels. Angels sacrificed for this purpose are not regained on reset of a game.

Example list (not actual):

3;ANGEL;10000;ALL;PROFIT;3
4;ANGEL;1e32;CAR_WASH;COUNT;100
5;ANGEL;3.4e134;ANGEL;EFFECTIVENESS;10

Resetting

---

When you reset your game, you lose all unlocks, upgrades, businesses, and money that you had. You start out with 1 lemonade stand all over again. So why would you want to do that? Because all angels that you may have earned last session are now activated. The angels that you didn't spend last session are also carried over. With these angels, you can earn larger profits faster than those earned in last session.

Lifetime earnings are not reset when you reset.

The angels gained with reset is 150 * sqrt(LIFETIME_EARNINGS / 1e15) - ANGELS - ANGELS_SACRIFICED

Bot Details

---

Your bot will be an independent program that sends and receives input and output through stdout, and stdin. They are allowed to write to and create files in the directory that they are in. All files that they create must be destroyed on death of the program. The program must be deterministic. If the program does not finish the game within 5 minutes, it is disqualified.

Your bot can send through stdout requests for information. Here is a list of each request along with the reply:

Request                                                                                    Reply
------------------------------------------------------------------------------------------------
TIME                                                                        game time in seconds
TIME_LEFT                                                              game time left in seconds
MONEY                                                                               cash on hand
LIFETIME_EARNINGS                                                              lifetime earnings
ANGELS                                                                             active angels
ANGELS_SACRIFICED                                       number of angels sacrificed in life-time
ANGELS_GAIN                                   number of angels that would be gained with a reset
COUNT type†                                                                       number of type
COST type†                                                                     cost of next type
PROFIT type†                                                               profit of all of type
UPGRADE or CASH_UPGRADE                                     the next cash upgrade you can afford
ANGEL_UPGRADE                                              the next angel upgrade you can afford
UPGRADES                                              the newline separated list of all upgrades
CASH_UPGRADES                                    the newline separated list of all cash upgrades
ANGEL_UPGRADES                                  the newline separated list of all angel upgrades
UPGRADE id                                                         the description of an upgrade
NEXT_UNLOCK type†                                                 the next unlock with type type
UNLOCKS                                                the newline separated list of all unlocks
UNLOCKS type†                           the newline separated list of all unlocks with type type
UNLOCK id                                                           the description of an unlock

_{† One of LEMONADE_STAND,NEWSPAPER_DELIVERY, CAR_WASH, PIZZA_DELIVERY, DONUT_SHOP, SHRIMP_BOAT, MOVIE_STUDIO, BANK, OIL_COMPANY, ALL}

These commands return no value:

Request                                                                                                  Action
---------------------------------------------------------------------------------------------------------------
WAIT seconds                                                                              warps forward in time
WAIT_MONEY x                                                                     waits until you have x dollars
WAIT_ANGEL x                                                                      waits until you have x angels
BUY type amount                 purchases items one at a time, waiting as needed until you can afford each item
RESET                                                                                        resets the session
BUY_UPGRADE id                                                                             purchases an upgrade
If you can't afford the upgrade it will wait until you can afford it if it is a CASH upgrade or will return 
immediately if it is an ANGEL upgrade

Format of an upgrade string: id;purchased[5];typeOfUpgrade[1];cost;bonus_string
Format of an unlock string: id;achieved[5];typeOfUnlock[2];amountNeeded;bonus_string
Format of a bonus string: type[3];subtype[4];amount

If subtype is PROFIT or COST, the bonus is applied multiplicatively, otherwise the bonus is applied additively.

_{[1]: One of CASH, ANGEL
[2]: One of LEMONADE_STAND,NEWSPAPER_DELIVERY, CAR_WASH, PIZZA_DELIVERY, DONUT_SHOP, SHRIMP_BOAT, MOVIE_STUDIO, BANK, OIL_COMPANY, ALL
[3]: One of ANGEL, LEMONADE_STAND,NEWSPAPER_DELIVERY, CAR_WASH, PIZZA_DELIVERY, DONUT_SHOP, SHRIMP_BOAT, MOVIE_STUDIO, BANK, OIL_COMPANY, ALL
[4]: EFFECTIVENESS if type is ANGEL; otherwise one of COUNT, PROFIT, COST
[5]: One of true or false}

Controller:

TODO

Score:

Your score is determined as log10(ANGEL_TOTAL). The person with the largest score wins the contest.

ANGEL_TOTAL is determined by adding all active angels, sacrificed angels, and the number of angels you would gain with a reset.

Leaderboard:

N/A

tag: code-challenge

Answer 20

Children Sum Game

code-golf

When I was a kid I liked to play a sum game with my cousin (I don't know if there's a name for the game).

The first player choose a number between 1 to 9, then by turns players go summing a number between 1 to 9 to the result until one is able to reach 100.

So, the challenge consist in create a program to play this game. The program has to choose randomly if the human or the computer starts the game. The player should input the sum of a number between 1 to 9 and the previous result and the program should check if the sum is correct. Then the program should sum another number between 1 to 9 and give the result. Finally it should display a message.

Here's a example of the game, suppose computer starts:

Computer: 5
Player: 12
Computer: 18
Player: 25
Computer: 30
Player: 39
Computer: 42
Player: 55
Computer: Incorrect sum!
Player: 48
Computer: 57
Player: 65
Computer: 73
Player: 82
Computer: 90
Player: 92
Computer: 100
You lose!

Ideally, the program should have a strategy to make it difficult (for a kid) to win the game.

Outputs should be: You win!, You lose! and Incorrect sum!

Answer 21

One Code, All the Challenges

This challenge has been abandoned due to poor wording. You may reclaim it if you wish without my permission.

tag: code-golf

Now, I always want to solve as many code-golfs as possible, so I thought "Why not solve them all at once?".

Your task

Create a block of code that solves another code-golf challenge on this Stack Exchange network. You must also make it so that when it is rotated (90°, 180° or 270°) it solves a different challenge on this website. Examples of rotated code-blocks:

0°       90°      180°     270°
AB       FCA      F G       EF 
CDE       DB      EDC      BD  
F G      GE        BA      ACG

The code golf that you are answering must have a shortest answer > 10 score (usually bytes). It may also not be a duplicate of another challenge.
Answers do not have to have a code-gold linked to every rotations, although this helps with score.

When rotating, take the shape that the code occupies, and rotate that. Some more examples:

0°       90°   | 0°      90°
print    p     | print   hsp
         r     | say~~   iar
         i     | hi by    yi
         n     |         b~n
         t     |         y~t

This means non-rectangular code is allowed, but whitespace (like-all other characters) except newlines must stay in-tact. This means the tildes (~) must be occupied with a character to allow for the rotate.

Scoring

Number of bytes in code * ((number of rotations that solve a challenge) * -2 + 7)
Lowest score wins.

Rotations | X   
        0 | Must work for at least one rotation
        1 | 5 
        2 | 3
        3 | 1
Number of bytes * X

Note
Please provide a link to each code golf question you are answering with each rotation. Also note that the questions answered must have been posted before this question, and each rotation must be in the same language. Also note if there are restrictions of source in one challenge, only the rotation that tries to solve that challenge has to comply with them.

Example:

Python 3, 21 bytes, 2 rotations, 63 points

0 degrees: https://codegolf.stackexchange.com/questions/4/print-hello-world
180 degrees: https://codegolf.stackexchange.com/questions/3/crash-the-program
(Don't put in links in ` ` in actual answers)

print("Hello world!")

0 degrees: prints the string 'Hello world!'
180 degrees: Crashes with a SyntaxError because of unopened close parenthesis.

Answer 22

Help the President!

Tags: code-golf

There is an anonymous president of a country who needs your help! He wants to retain absolute control, but needs to have elections to prevent uprisings. They ask you to create a program to help them gerrymander.

These are the specifications:

Input

(You will receive input via stdin or as a function argument)

You will be given an array of arrays of strings to represent the locations of voters (a 2D matrix), i.e:

[["Democratic", "Republican", "Republican", "Democratic"],
 ["Republican", "Democratic", "Democratic", "Democratic"],
 ["Democratic", "Republican", "Democratic", "Republican"],
 ["Democratic", "Republican", "Republican", "Republican"]]

Which is

[["Democratic", "Republican", "Republican", "Democratic"], ["Republican", "Democratic", "Democratic", "Democratic"], ["Democratic", "Republican", "Democratic", "Republican"], ["Democratic", "Republican", "Republican", "Republican"]]

You will also receive a party that is meant to win, like "Democratic" or "Republican". These will be in the matrix.

Thirdly, you will receive district sizes. The amount of items in the matrix will be a multiple of this. All districts must be this size.

Output

An array of arrays of coordinates. Either the top left or the bottom left may be [0, 0] or [1, 1]. Going right increases the second number and going down / up increases / decreases the first number.

This country uses a first-past-the-post voting (Most votes win) per district (except if there is a tie, none of them win). You must split the matrix of voters into districts in such a way that the party wins as many districts as possible. A district is given by one of the arrays in the output. Districts must be contiguous, and going diagonally is not contiguous. Some visualisations by this helpful CGP Grey video on Gerrymandering and one example outputs:

f([["D", "R", "D"], ["D", "D", "R"], ["D", "D", "R"]], "D", 3)
[[[0, 0], [0, 1], [1, 0]], [[0, 2], [1, 1], [1, 2]], [[2, 0], [2, 1], [2, 2]]]
# In this case, the D party wins all of the votes.
f([["D", "R", "D"], ["D", "D", "R"], ["D", "D", "R"]], "R", 3)
[[[0, 0], [0, 1], [0, 2]], [[1, 0], [1, 1], [1, 2]], [[2, 0], [2, 1], [2, 2]]]
# R wins a third of the seats

This demographic could be visualised as

D  R  D
D  D  R
D  D  R

(Note there may be many possible "best" district boundaries. In this case, return any of them. And in a case where there are two cases that give the party the same amount in both cases, but the second case gives a smaller majority to another party, return the latter)

f([["B", "R", "B", "R", "B"], ["G", "B", "G", "R", "Y"], ["G", "R", "Y", "B", "Y"], ["B", "G", "B", "G", "Y"]], 4, "Y")
[[[0, 0], [1, 0], [1, 1], [2, 0]], [[0, 1], [0, 2], [0, 3], [0, 4]], [[1, 2], [1, 3], [1, 4], [2, 3]], [[2, 1], [3, 0], [3, 1], [3, 2]], [[2, 3], [2, 4], [3, 3], [3, 4]]]
# In this election, Y wins 2, B wins 1 and 2 are undecided

Sandbox notes

This seems way too wordy for a problem which seems so simple. Any areas where it could be clarified to be more concise? I think it's my organisation of stuff that makes it unclear.

Answer 23

Cooperative Tamagotchi

This is a new twist to the Tamagotchi-style ideas floating around. I also plan on creating a "no rules" version, but the cooperative version is the more complete idea at the moment.

---

Tamagotchi, more popularly known as StackEgg, is a game in which you nurture the growth of an adorable pet, also more popularly known as PPCG. The pet has a set of statistics which reflect the health and well-being of the pet. You also have a series of buttons. When you press a button, the pet's stats are affected. One stat receives a boost, but the other stats that did not receive a boost slowly wither away.

In the game, your goal is to work together to win a game of Tamagotchi. Each contestant program casts votes to determine which move will be played in a given game cycle. This is a competition, however, because your personal contributions are being measured. If you vote for a move, and that move wins the election, then the effect of the move will affect your score. If the action was beneficial to your pet, you gain points. If the action was detrimental to your pet, you will lose points.

---

I don't have a "theme" for the Tamagotchi yet. Here are some ideas for how it would work. I could alternatively wait for the source for StackEgg to be released or reverse-engineered and use those more realistic rules.

There would probably be a single game phase, probably based on the "full site" phase of StackEgg in terms of functionality. This means that there are five stacks and five "constructive" buttons.

Each stat has two numbers: the number of hearts, which is visible, and a decay counter, which is hidden. When calculating a player's positive or negative contribution, only the number of hearts is used (?).

More details coming sometime not now.

Answer 24

Quine Creator

quinecode-golf

The program F is in language A. F takes a program in language B as input. Lets call this program G. F outputs a program in language B. Lets call this program O. O Takes some input and for some values it will be a quine and for others it will run G.

The exact values which O decides behaviour must be the same for each different input to F but you can decide what the conditions will be. They must be short (5 or less bytes), reasonable and not turned into code and executed for the sake of a shorter program F. Acceptable behaviours include (but are not limited to):

• Quines for even digit, G for odd
• Quines for truthy input, G for anything else
• Quines for the input "0", G for anything else

For example your program F could be written in Java and take a Python program (G) as input and output a program in Python (O) that runs G when given at least 1 arg and prints it's source when not given any args.

Sorry if this is a bit confusing

Answer 25

Find sequences in RSA_1024

I found an interesting way to factor numbers, while its far from been any efficient in compare to other known methods, its lots of fun!

Lets assume we want to factor N. X will be its factor, if and only if

N/X = floor(N/X)

So theoretically, if you could find a different representation of floor(N/X), you could easily find X, so while find such representation is unlikely it is very easy to find it within a small range, for example take a look at floor(N/X) of N = 691 ∗ 983 = 679253

At left is X at right is floor(N/X) - floor(N/(X+1))

512 2 
513 3 
514 3 
515 2 
516 3 
517 2 
518 3 
519 2 
520 3 
521 2 
522 3 
523 2 
524 3 
525 2 
526 3 
527 2 
528 2 
529 3 
530 2 
531 3 
532 2 
533 2 
534 3 
535 2 
536 3 
537 2 
538 2 
539 3 
540 2 
541 2 
542 3 
543 2 
544 2 
545 2 
546 3 
547 2 
548 2 
549 2 
550 3 
551 2 
552 2 
553 2 
554 3 
555 2 
556 2 
557 2 
558 2 
559 3 
560 2 
561 2 
562 2 
563 2 
564 2 
565 2 
566 3 
567 2 
568 2 
569 2 
570 2 
571 2 
572 2 
573 2 
574 2 
575 2 
576 2 
577 2 
578 2 
579 2 
580 2 
581 2 
582 2 
583 2 
584 2 
585 2 
586 2 
587 2 
588 2 
589 2 
590 2 
591 2 
592 2 
593 2 
594 2 
595 2 
596 2 
597 2 
598 2 
599 1 
600 2 
601 2 
602 2 
603 2 
604 2 
605 2 
606 1 
607 2 
608 2 
609 2 
610 2 
611 2 
612 1 
613 2 
614 2 
615 2 
616 2 
617 1 
618 2 
619 2 
620 2 
621 1 
622 2 
623 2 
624 2 
625 1 
626 2 
627 2 
628 2 
629 1 
630 2 
631 2 
632 1 
633 2 
634 2 
635 1 
636 2 
637 2 
638 2 
639 1 
640 2 
641 1 
642 2 
643 2 
644 1 
645 2 
646 2 
647 1 
648 2 
649 1 
650 2 
651 2 
652 1 
653 2 
654 1 
655 2 
656 2 
657 1 
658 2 
659 1 
660 2 
661 1 
662 2 
663 2 
664 1 
665 2 
666 1 
667 2 
668 1 
669 2 
670 1 
671 2 
672 1 
673 2 
674 1 
675 2 
676 1 
677 2 
678 1 
679 2 
680 1 
681 2 
682 1 
683 1 
684 2 
685 1 
686 2 
687 1 
688 2 
689 1 
690 1 
691 2 
692 1 
693 2 
694 1 
695 2 
696 1 
697 1 
698 2 
699 1 
700 2 
701 1 
702 1 
703 2 
704 1 
705 1 
706 2 
707 1 
708 1 
709 2 
710 1 
711 1 
712 2 
713 1 
714 1 
715 2 
716 1 
717 1 
718 2 
719 1 
720 1 
721 2 
722 1 
723 1 
724 2 
725 1 
726 1 
727 1 
728 2 
729 1 
730 1 
731 2 
732 1 
733 1 
734 1 
735 2 
736 1 
737 1 
738 1 
739 2 
740 1 
741 1 
742 1 
743 2 
744 1 
745 1 
746 1 
747 1 
748 2 
749 1 
750 1 
751 1 
752 1 
753 2 
754 1 
755 1 
756 1 
757 1 
758 2 
759 1 
760 1 
761 1 
762 1 
763 1 
764 2 
765 1 
766 1 
767 1 
768 1 
769 1 
770 1 
771 2 
772 1 
773 1 
774 1 
775 1 
776 1 
777 1 
778 2 
779 1 
780 1 
781 1 
782 1 
783 1 
784 1 
785 1 
786 1 
787 2 
788 1 
789 1 
790 1 
791 1 
792 1 
793 1 
794 1 
795 1 
796 1 
797 1 
798 1 
799 1 
800 1 
801 2 
802 1 
803 1 
804 1 
805 1    
806 1 
807 1 
808 1 
809 1 
810 1 
811 1 
812 1 
813 1 
814 1 
815 1 
816 1 
817 1 
818 1 
819 1 
820 1 
821 1 
822 1 
823 1 

Its easy to tell that in the range of 566,599 floor(N/X) act like a strait line y = 2x + 566. Also it's easy to verify as we can calculate the difference between floor(N/566) and floor(N/599) and see if its equal to 2 * 599 - 566, and indeed it is.

So now lets play

Input

Your input is the number RSA_1024, while we will only use this input, your app should be able to work with any other inputs as well.

Output

10,000 sequences that you found starting from Sqr(RSA_1024) and going up. Each sequences will be outputted in a new line. For each sequences you should output the next

• starting range value
• end range value
• type

Type is just a string defined by you that tells us what kind of sequence is it, strait-line or some thing else.

After you output the sequences, output one line with the total range you been able to cover with all the sequences.

Criteria

Who covers the biggest Range wins.

Answer 26

Realistic Fractal Terrain Generation

popularity-contestgraphical-output

Don't you find that typical algorithms to generate random fractal terrains are boring and not too much realistic?

Fractal terrain generation is usually implemented with some random noise function applied in a fractal way. This can be seen with the typical Diamond-Square algorithm or the Perlin Noise function:

Diamond-Squares example output:

Perlin noise example output:

The problem is that these are used by their simplicity in creating them, but they are actually pretty boring when they are used as height maps:

... To be continued ...

Answer 27

Make a fighter, then have them battle

Well, I was browsing around KOTH one day. I found two little interesting challenges: Save the last bullet for yourself and Codémon, I choose you!. But what if we combined the two?

How your bot will work

Each match, your bot is assigned an opponent. It is randomly decided who goes first. Your bot is given HP of 100. You must output:
ATKID DEFID MOVED ATKDIR DEFDIR
ATKID is the attack's ID, and DEFID is the defense (or support) ID, for skills. MOVED is your move direction, on a number-pad (5 being 'stay still'). ATKDIR and DEFDIR are attack and defense skill directions (for Bullet, Wall, etc.)
Your bot must accept the following as input:
MYHP YOURHP MYPOS YOURPOS (additional projectile positions)

Your bot is allowed 2 attack and 2 defense skills.
List of attack skills:

0: Attack: Deal 10 damage.
1: Psychic Blast: Deal 5 damage this turn and 5 damage the next.
2: Bullet: Fire off a bullet that damages for 15 points when it hits an enemy.
3: Hadouken: Fire of a large flaming ball that can fly for 3 squares, and deals 50 damage.

List of defense skills:

0: Block: Block up to 10 points of damage this turn.
1: Heal: Heal for 10 points.
2: Wall: Add a wall in target direction.

How the arena works

The arena starts as follows:

==========
|        |
|        | 
|a      b|
|        |
|        |
==========

where a and b are bots' starting positions.

Meta Questions

• What should I add as skills? Healing? Defensive?
• Is the arena too small?
• Have I left out any restrictions?
• Can I have some help with the 2D grid?
• Is the input/output sufficient?
• Does anyone want to pick up this challenge? I already have another KOTH, this was just an idea everyone liked.

Answer 28

Missing distance between points

code-golf error-correction and-some-other-tags

There are N points on a straight line. Someone calculates all possible distances between each pair of points and sort them.

In the following example I used 5 points. The sorted list of distances is [2, 5, 6, 8, 9, 14, 15, 17, 20, 22].

---X--X------X---------X-----X---

   |-2|---6--|----9----|--5--|
   |-----8---|-------14------|
      |--------15------|
   |---------17--------|
      |----------20----------|
   |----------22-------------|

You will receive the list, but one of the numbers is unreadable. This will be indicated by a zero. So you might receive the list [2, 5, 6, 8, 9, 0, 15, 17, 20, 22]. Your job is to find the missing number.

Input / Output:

Write a function/program that finds the missing number. The input (via STDIN, command-line argument, prompt or function argument) format is a list or an array of distances (integers). You can optionally take the number of points (one integer) as a second parameter if you want. The output (via return value or STDOUT) is one single integer, namely the missing number in the distances list.

This is code-golf. Therefore the shortest code wins.

Test cases:

#points, distances -> output
5, [2, 5, 6, 8, 9, 0, 15, 17, 20, 22] -> 14
3, [1, 0, 2, 2, 3, 4] -> 2
...

Sandbox notes:

• This challenge is based on one problem of this year's Mathematical Kangaroo. My dad is a math teacher and brought me a copy of the 7.-8. grades test.

• Example and test cases don't look pretty and will be improved and extended for the final question on PPCG.

• My main concern about the challenge is the speed of the programs. My first (and only) solution is quite slow, because of the bad time complexity (about (n^2)^(n-1), where n is the number of points on the line). The 5-point example takes already about 1 second to compute, a 6-point example took about 10 minutes. My guess is, that most code-golf solutions will use a similar approach and the programs may be quite difficult to test.

  There's definitely a better way of computing the missing number.

  Maybe I'll add a few big testcases (one with 6, 7, 8, 9 and 10 points) and promise a 50% bonus if the program can solve all test-cases in under one minute.

Answer 29

Shadows to Height Maps

The goal of this code challenge will be to take a grayscale image with shading as input and produce a height-map image with the same dimensions as output.

The input image will be a grayscale 256x256 png image, shaded with only a diffuse term, no ambient or specular term. It will be lit by a directional light source hitting the surface at a 45 degree angle, from above.

The output must be a 256x256 png image containing the height-map.

This is a code-challenge, the answer with the most accurate results wins. (A perfect match between the reverse engineered height-map and the original height-map used to produce the shaded image is near impossible, it is not expected that they are identical).

(working on test cases)

tags:

image-processing, code-challenge, graphical-output, conversion

Answer 30

SVG file optimization

Yep, I got my idea off of this question, and it's amazing answer. All credit for this question goes to Illmari Karonen's answer

Now, for the challenge: Write a program that removes unnecessary clutter from SVG files in order to reduce their byte counts.

1. Remove comments <!-- comment -->
2. remove metadata <metadata ...> </metadata>
3. Shorten necessary ids to 1 letter, and remove unused ids.
4. remove unnecessary attributes and XML namespace attributes

Any other methods used to shorten the SVG files are welcome. (You can refer to the linked answer to look at an extensive list of ways to shorten SVG files)

Your program's score is how many bytes it removes from these SVG files:

test cases in progress