Sandbox for Proposed Challenges

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Answer 1

Calculate Pi unto a Point using the Nilakantha series

Answer 2

Title

God Save the Queen (or King)!

Input

A calendar year from 927 to the present year. For example 2022.

Output

You can use any three distinguishable outputs. As an example,

“K” (short for King)

or

“Q” (short for Queen)

depending on which was right in England in that year. If there was both a King and Queen in that year you can output either.

If there was no King or Queen for the whole of that year, your code must output something that is not one of those two messages.

Dates

Kings: 937-1553, 1603-1649, 1660-1702, 1714-1837, 1901-1952, 2022

Queens: 1553-1603, 1689-1694, 1702-1714, 1837-1901, 1952-2022

code-golf

Answer 3

Is there a area that can see the entire perimeter of a polygon code-golfgeometrydecision-problem

Oh no, your despotic regime has too many political prisoners and not enough guards! Time for drastic measures: Only build prisons that require only a single guard. But there are many prison design and little time. How to check?

The challenge

Given a polygon, as a list of points, determine if there is a area (where the guard can stand) that can see the entire perimeter of the polygon.

Any convex shape trivially qualifies:

Some concave shapes qualify too:

But not all:

Algorithm hint

The area where a guard can stand is the intersection of the areas on the inside of the tangent of every edge.

Test Cases

Image	Points	Outcome
	TBD

Answer 4

Calculating Pi using the Gregory-Leibniz series unto a point

Answer 5

Construct Digit From Digits

In the game All Ten, each day you are given four single-digit positive integers, and have to use all four of those numbers once each to construct the values 1 through 10 using the following operations:

• Addition
• Subtraction
• Multiplication
• Division
• Concatenation, i.e. joining two numbers together; for example, \$1 \text{ concat } 23 = 123\$. (You can only apply this operation if both of the numbers are integers and the number on the right is non-negative.)

So, for example, given numbers \$[4,4,8,9]\$, to make \$4\$ you could do \$((4 \text{ concat } 4) - 8 ) / 9\$. which equals \$(44 - 8)/9 = 36 / 9 = 4\$.

You're allowed to compose these operations however you want, in whatever order, including concatenation (e.g. you can do \$16 - ((2-1) \text{ concat } 3) = 16 + (-1 \text{ concat } 3) = 16 - 13 = 3\$.)

The challenge:

Your function is given two inputs: \$I\$, which is a list of four single digit positive integers (i.e. in the range \$1,2,\ldots,9\$) which are not necessarily unique, and \$n\$, which is also a single digit positive integer.

Your function should return a way of using all four numbers in \$I\$ to construct \$n\$ using the rules above.

Output Format

You can provide the output in any meaningful way, including:

• A string (or list of numbers/characters) representing the expression which evaluates to \$n\$, using any symbols besides \$1,2,\ldots,9\$ to represent the operations / parentheses necessary
  • e.g. "((4c4)-8)/9"
  • You're also allowed to represent concatenation with the empty string (i.e. no operator at all) -- e.g. "((44)-8)/9"
  • You can leave out parentheses if you specify the order of operations -- e.g. you say that concatenation has highest priority, then return "(44-8)/9"
• A tree or nested list with where each leaf represents a number in \$I\$ and the parents represent the various operations

You may assume there is at least one solution; if there's more than one solution, you may output any of them.

Test cases

[To do -- I need to enumerate all of the possible ways to construct a given value for this to be useful.]

Questions

This is a really bad title, but it's hard to describe succintly. There's also a lot of text here, but I don't know how to shorten it.

Answer 6

Create a nibble shorthand

Answer 7

Longest alternating subsequence

Answer 8

Partition square into squares

Given integers \$n\$, \$m\$ and \$k\$, randomly output a list of \$k\$ numbers between \$1\$ and \$m\$ (inclusive) such that the sum of the squares of the numbers in the list is equal to \$n\$ squared. In other words, find a way to randomly split \$n^{2}\$ into \$k\$ squares between \$1\$ and \$m^{2}\$.

If there is no solution (which may happen if \$k = 2\$), you may exit from your program or return an error.

The program should take less than 40 seconds for inputs with \$k, n, m\$ less than 10000.

Scoring

This is code-golf, so the smallest score in bytes wins.

Input

Three numbers \$n\$, \$m\$, and \$k\$.

Output

A random list of \$k\$ numbers between \$1\$ and \$m\$, such that the sum of the squares of them is equal to \$n^{2}\$. All possible lists that satisfy the conditions should be equally likely.

Test cases

Input (n, m, k)      Possible output
114, 100, 6          [13, 1, 25, 76, 44, 67]
114, 100, 6          [64, 58, 20, 32, 64, 4]
57, 40, 7            [2, 32, 18, 26, 26, 17, 16]
7, 10000, 2          [error]
7, 7, 3              [2,3,6], [2,6,3], [3,2,6], [3,6,2], [6,2,3], [6,3,2]

Answer 9

Prime number checksum

Posted here

Answer 10

Alphabet checksum

Answer 11

Render an Ideographic Description Sequence

codegolf graphical-output unicode

There are 12 characters in Unicode that can be used to describe any CJK character, which are often made up of reoccurring parts ("radicals") composed in different ways.

For example, U+86D9 蛙 can be described as U+2FF0 U+866B U+572D ⿰虫圭.

Your task is to take such an Ideographic Description Sequence as input and produce an image of the resulting character as an output. You can assume the input conforms to the following grammar, which is taken from the Unicode standard, which explains this topic very well:

IDS := Ideographic | Radical | CJK_Stroke | Private Use | U+FF1F
    | IDS_BinaryOperator IDS IDS
    | IDS_TrinaryOperator IDS IDS IDS
CJK_Stroke := U+31C0 | U+31C1 | ... | U+31E3
IDS_BinaryOperator := U+2FF0 | U+2FF1 | U+2FF4 | ... | U+2FFA | U+2FFB
IDS_TrinaryOperator := U+2FF2 | U+2FF3

This is a kind of prefix notation (polish notation).

Ideographic and Radical are defined in PropList.txt:

2E80..2E99    ; Radical # So  [26] CJK RADICAL REPEAT..CJK RADICAL RAP
2E9B..2EF3    ; Radical # So  [89] CJK RADICAL CHOKE..CJK RADICAL C-SIMPLIFIED TURTLE
2F00..2FD5    ; Radical # So [214] KANGXI RADICAL ONE..KANGXI RADICAL FLUTE

3006          ; Ideographic # Lo       IDEOGRAPHIC CLOSING MARK
3007          ; Ideographic # Nl       IDEOGRAPHIC NUMBER ZERO
3021..3029    ; Ideographic # Nl   [9] HANGZHOU NUMERAL ONE..HANGZHOU NUMERAL NINE
3038..303A    ; Ideographic # Nl   [3] HANGZHOU NUMERAL TEN..HANGZHOU NUMERAL THIRTY
3400..4DBF    ; Ideographic # Lo [6592] CJK UNIFIED IDEOGRAPH-3400..CJK UNIFIED IDEOGRAPH-4DBF
4E00..9FFF    ; Ideographic # Lo [20992] CJK UNIFIED IDEOGRAPH-4E00..CJK UNIFIED IDEOGRAPH-9FFF
F900..FA6D    ; Ideographic # Lo [366] CJK COMPATIBILITY IDEOGRAPH-F900..CJK COMPATIBILITY IDEOGRAPH-FA6D
FA70..FAD9    ; Ideographic # Lo [106] CJK COMPATIBILITY IDEOGRAPH-FA70..CJK COMPATIBILITY IDEOGRAPH-FAD9
16FE4         ; Ideographic # Mn       KHITAN SMALL SCRIPT FILLER
17000..187F7  ; Ideographic # Lo [6136] TANGUT IDEOGRAPH-17000..TANGUT IDEOGRAPH-187F7
18800..18CD5  ; Ideographic # Lo [1238] TANGUT COMPONENT-001..KHITAN SMALL SCRIPT CHARACTER-18CD5
18D00..18D08  ; Ideographic # Lo   [9] TANGUT IDEOGRAPH-18D00..TANGUT IDEOGRAPH-18D08
1B170..1B2FB  ; Ideographic # Lo [396] NUSHU CHARACTER-1B170..NUSHU CHARACTER-1B2FB
20000..2A6DF  ; Ideographic # Lo [42720] CJK UNIFIED IDEOGRAPH-20000..CJK UNIFIED IDEOGRAPH-2A6DF
2A700..2B739  ; Ideographic # Lo [4154] CJK UNIFIED IDEOGRAPH-2A700..CJK UNIFIED IDEOGRAPH-2B739
2B740..2B81D  ; Ideographic # Lo [222] CJK UNIFIED IDEOGRAPH-2B740..CJK UNIFIED IDEOGRAPH-2B81D
2B820..2CEA1  ; Ideographic # Lo [5762] CJK UNIFIED IDEOGRAPH-2B820..CJK UNIFIED IDEOGRAPH-2CEA1
2CEB0..2EBE0  ; Ideographic # Lo [7473] CJK UNIFIED IDEOGRAPH-2CEB0..CJK UNIFIED IDEOGRAPH-2EBE0
2F800..2FA1D  ; Ideographic # Lo [542] CJK COMPATIBILITY IDEOGRAPH-2F800..CJK COMPATIBILITY IDEOGRAPH-2FA1D
30000..3134A  ; Ideographic # Lo [4939] CJK UNIFIED IDEOGRAPH-30000..CJK UNIFIED IDEOGRAPH-3134A
31350..323AF  ; Ideographic # Lo [4192] CJK UNIFIED IDEOGRAPH-31350..CJK UNIFIED IDEOGRAPH-323AF

Rules

Keep in mind that output has to be an image, not a unicode character, as per the default loophole, but I recommend a text rendering engine to render each radical.

You can assume the input won't contain private use characters.

Use the following definitions of the Ideographic Description Characters. The percentages are not defined in unicode, but made up for this challenge. Each component should be squashed to the required shape, so that each intermediate result is a square. The output should also be a square image. See also: https://en.wikipedia.org/wiki/Chinese_character_description_languages#Ideographic_Description_Sequences

Code point	Character	Meaning
U+2FF0	⿰	divide horizontally in halves
U+2FF1	⿱	divide vertically in halves
U+2FF2	⿲	divide horizontally in thirds
U+2FF3	⿳	divide vertically in thirds
U+2FF4	⿴	enclose; the lengths should be 20%, 60%, 20%
U+2FF5	⿵	surround from top; the inner has 60% the width and 80% of the height
U+2FF6	⿶	surround from below; the inner has 60% the width and 80% of the height
U+2FF7	⿷	surround from left; the inner has 80% the width and 60% of the height
U+2FF8	⿸	surround from top-left; the inner has 80% the width and height
U+2FF9	⿹	surround from top-right; the inner has 80% the width and height
U+2FFA	⿺	surround from top-right; the inner has 80% the width and height
U+2FFB	⿻	overlay with transparency

Examples

Input	Output
虫	虫
鬱	鬱
⿰虫圭	蛙
⿲彳圭亍	街
⿵几皇	凰
⿻工从	巫
⿴囗⿰⿱鹵凼⿰丨㇌
⿱井蛙
⿱井⿰虫圭
⿱井⿰虫⿱土土

Answer 12

Increment, decrement, undo, peek

Answer 13

Length of Binary as Base 10 [OEIS A242347]

Answer 14

Power sequence differences

Answer 15

Longest Total Distance Cyclic Quine Chain code-challengequinebusy-beaver

Write a program of upto 100 bytes that outputs another program that outputs another program etc. until after a finite number of iterations outputting the original program again.

Each program in the cycle must have a length less than or equal to 100 bytes.

Your score is the sum of the Levenshtein distance between each program and it's output. I hope this leads to answers that do something more creative than change a single digit each time.

Maximum possible score is: $$256^{101}$$

Answer 16

Perfect Nontransitive Sets

Answer 17

Number to letters

Answer 18

Is it a legal atomic chess move?

Answer 19

Print the most uncommon character

code-golf self-referential

Your task is to write a full program or function that prints the character(s)* that appears in your code the least. For example, if my code was AAAABBBBCCCDDD, then the program should print CD or DC.

Rules

• All printed characters must appear at least three times in your code, but you will print only one character for each.
• You are only printing those character(s). If your language always includes a trailing newline, then that is allowed.
• All printed characters must be printable characters or newlines.
• If multiple characters all appear the least, you must print them all, without separation. Order does not matter.
• The program or function cannot be empty, so it has to be a minimum of three characters long.
• This is code-golf, so the shortest code in bytes wins.

_{*Where "character(s)" is mentioned in the rules above, exceptions may be made for languages like TI-Basic or Piet which do not use characters.}

Meta

• Are there any similar questions to this?
• Should I change the rules?

Answer 20

Find the nth number where the digit sum equals the number of factors

Answer 21

Range of ASCII values

Answer 22

Join Columnar Strings

Tags: code-golfstring

Answer 23

Merged strings

Not sure if this is already done

Basically, take two strings of reasonable length (like <32 chars) of numbers and X's and find the shortest superposition of those strings such that there's no 2 numbers at the same position. Number+X or X+X is allowed. Print the result.

Examples:

["01XX02","10XX2"]
-----
010X02

["5234XXX","431XXX"]
-----
523431XXX

Note:

• Even if the string ends with X's, print those X's as they're part of the strings.
• Oh and the result must start with the first string. (like test 4)

Tests:

1234   | 345    -> 12345
6573   | 2625   -> 65732625
11X    | 12     -> 112
XX1XX  | XX2XX  -> XX12XX
X1X2X3 | 1XX234 -> X1X2234

Scoring

The program with the least bytes wins!

Answer 24

><> numbers metagolf coding-challengemeta-golfrestricted-complexity

Answer 25

KotH: Don't Kill the Curve!

In this KotH, you will take a test at school. Your goal, of course, is to get the highest grade, up to a maximum of 110%. This score consists of your actual grade, curved, as well as 10% which is the average of other students' scores, since your teacher wants to encourage students to study together.

You have a minimum of 100 turns leading up to the test. You can use these to either:

• Study: This add a point to your score (initially 0), unless your score is already 100
• Tutor: Adds two points to the score of any other student, up to a max of 100
• Arson: Majorly disrupt another student's life, dropping their score by 10 points (down to a minimum of zero), and negating their next 10 actions as they rebuild their life

Arson requires a lengthy jail sentence, meaning that your next 10 actions are also negated. If you have fewer than 10 actions left, you miss the test, and must retake it, making the maximum score you can receive (after the curve, before the bonus from other students) 70 points. Your real score is still used in the class average. Note that being an arson victim in the last 10 turns does not prevent you from taking the test; it only prevents you from studying, tutoring, or paying it forward.

You can also miss the test by taking more than 100 turns. After 100 turns you can only tutor or commit arson against other students which have not yet taken the test. Missing the test normally still has the same impact as if you had missed it while in jail, so it is likely only an effective strategy if you would otherwise receive a score below 70 (perhaps due to being an arson victim or avid tutor).

The test is also curved. Whichever student has the highest raw score will have theirs adjusted to 100, and that same shift will be applied to all other students. The curve is not taken into account for student averages, so if all students receive a 20% raw score, they would receive 102% as their final score (if they did not miss the test).

Information:

You are aware of all other students' scores on previous tests, your own "preparedness" (the raw score you would get if you took the test now), and the list of students who are recovering from arson and/or in jail.

Answer 26

Smallest and largest 100-bit square with maximum Hamming weight

Answer 27

Two-leg train journey

Joseph wants to travel by train from town A to town C. There is no direct train, so he wants to transfer in town B. You get the railway timetables from A to B and from B to C, and the latest time when Joseph needs to arrive to C. Compute the latest time that Joseph can arrive to the railway station in A and still be in time.

Times are given as integers between 0 and 1440, meaning the number of minutes from midnight on the day of the journey. A schedule from a town to another is given as a list of pairs, each pair made of two times, namely the time when the train departs from the first station and the time when it arrives to the second station. Your program gets three inputs: the train schedule from town A to town B, the train schedule from town B to town C, and the time when Joseph has to arrive to C the latest. Your program must output a single time, namely the latest time when Joseph has to be on station A.

The transfer at B is immediate, so if the first train arrives to B at exactly the same time as the second train departs from B then Joseph can transfer. You can assume that there are enough trains that Joseph can arrive at the required time or earlier. You can also assume that each schedule is sorted by departure time, but you cannot assume that the schedule is sorted by arrival time. For example, in the example input below, the first train from B departs at time 319 (meaning 09:27) and arrives at time 567 (meaning 9:27), but the second train departs at 366 and arrives at 539, overtaking the first train. Joseph is in a hypothetical country where trains always run exactly in time according to their schedule.

Here's a non-golfed example solution in Python 3. The function transfer solves the problem. The function travel takes just one schedule and finds when you have to arrive to the station where the trains in that schedule start.

def travel(schedule, arrival):
    departure = -2000
    for train in schedule:
        if train[1] <= arrival and departure < train[0]:
            departure = train[0]
    return departure
def transfer(schedule0, schedule1, arrival1):
    return travel(schedule0, travel(schedule1, arrival1))

Here's how we invoke the above example solution with an example input triple.

print(transfer(
    ((270, 294), (337, 357), (390, 414), (457, 477), (510, 534), (577, 597), (630, 654), (697, 717), (750, 774), (817, 837), (870, 894), (937, 957), (990, 1014), (1057, 1077), (1110, 1134), (1230, 1254), (1338, 1362)),
    ((319, 567), (366, 539), (540, 714), (545, 809), (780, 954), (785, 1055), (900, 1074), (905, 1169), (1025, 1280), (1140, 1324)),
    720))

This prints 510, which is the correct output for these inputs. In station A, Joseph will take the train at time 510 (meaning 08:30), arrive to B at time 534 (08:54), get on the second train at time 540 (09:00), and arrive to C at time 714 (11:54), which is not later then the deadline time 720 (12:00).

This is a slightly modified version of an easy programming homework problem that I posed many years ago. I am shamelessly copying the single example input from there, since I'm too lazy to make up a new one.

Golf Sandbox, besides all the other feedback, please tell me what tags I should use.

Answer 28

A decimal-based unit of time

Answer 29

Is this position a pure mirror mate?

Answer 30

Flip the order of operations code-golf