Sandbox for Proposed Challenges

Question

This "sandbox" is a place where Code Golf users can get feedback on prospective challenges they wish to post to main. 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.

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Answer 1

Flexagonal datastructures

Being programmers, watching us flex aren't very interesting. Today we change that! In this challenge you will lex and flex hexaflexagons.

About

For a video introduction, watch viharts video(s) on flexagons

A flexagon is a shape that you can flex to reveal faces other than the top and bottom one; we are making a hexahexaflexagon, which has 6 faces. See the image below on how to fold a hexahexaflexagon out of a strip of paper.

A shows both sides of the strip. The two white triangles are glued together. This is how you would flex it:

Below is a diagram of possible states and their relationships:

The colored circles represent the 6 triangles with the same number from the first image. Each of the circes have two colors- the bottom most represent the back face (what you would see if you where to flip your flexagon around), which you don't have to consider in this challenge.

The gray circles represent how you can flex your flexagon in any given state: there are 4 different ways to flex it, we call these Left, Right, Up and Down. You don't actually flex in these directions, the important bit is that some are opposite to each other.
If you are in the center you can use Left and Right to go to the other center ones. To get out of the center you use Up and Down. If you aren't in the center you cannot use Left or Right.

Left/Down = clockwise
Right/Up  = anti-clockwise

Challenge

Create a function or program that take as input what should be on the 18 front faces and the 18 back faces of a flexagon, a sequence of left, right, up and down flexes, and return the 8 visible faces after the flexes.

Example computation:

flex "hexaflexaperplexia" 
     "flexagationdevices" 
     [Right, Right, Left]

Divide a strip of paper into 19 triangles:
1/2\3/1\2/3\1/2\3/1\2/3\1/2\3/1\2/3   Front
4/4\5/5\6/6\4/4\5/5\6/6\4/4\5/5\6/6   Back

Write "hexaflexaperplexia" to the front of the paper strip:
1/2\3/1\2/3\1/2\3/1\2/3\1/2\3/1\2/3

hexaflexaperplexia
123123123123123123
h  a  e  p  p  x     Face 1, Initially the front face
 e  f  x  e  l  i    Face 2, Initially the back face
  x  l  a  r  e  a   Face 3, Initially hidden


Write "flexagationdevices" to the back of the paperstrip:
4/4\5/5\6/6\4/4\5/5\6/6\4/4\5/5\6/6

flexagationdevices
445566445566445566
fl    at    ev       Face 4, up from 3
  ex    io    ic     Face 5, up from 2
    ag    nd    es   Face 6, up from 1


Flex it [Right, Right, Left]
  The initial visible face is 1: "haeppx"
  flexing Right ..
  The current visible face is 2: "efxeli"
  flexing Right ..
  The current visible face is 3: "xlarea"
  flexing Left ..
  The current visible face is 2: "efxeli"
  flexed [Right, Right, Left]!

outputting "efxeli"

Example input and expected output:

> hexaflexaperplexia flexagationdevices RRL
= efxeli

> loremipsumdolorsit hexaflexamexicania LUU
= riuort

> abcdefghijklmnopqr stuvwxyz1234567890 UL
= I can't flex that way :(

> abcdefghijklmnopqr stuvwxyz1234567890 RRRRLLUDDUUUULDD
= uv1278

Rules

• You may take input and return output in any reasonable way
• If the input is impossible, you should indicate so in some way that is distinct from regular output
• Standard loopholes apply
• This is Codegolf. Shortest code in bytes win.

Answer 2

Draw me a Brick Wall!

I'm drawing up a plan for my house extension - and I need a simple graphic for walls...

The Challenge

Your task is to create a program, which takes an input of the wall's dimensions and draws a brick wall, in the style of the one below.

[__][__][__][__]
_][__][__][__][_
[__][__][__][__]
_][__][__][__][_
[__][__][__][__]
_][__][__][__][_

Please notice that the rows alternate between beginning on a full brick ([__]) and a half brick (_]), to create a more realistic, stable wall.

The input will be two integers, separated by a single comma, such as 4,3 or 2,6. You can assume both integers are positive and larger than 0.

The first integer specifies the width (in bricks) and the second specifies the height (in rows of bricks).

Rules / Notes

• This is code-golf, so the shortest code (in bytes) wins. However, don't feel like you have to beat everyone else to post your solution - I'd love to see your code!
• Standard loopholes apply, no reading from external files.
• You may optionally take the input with brackets/braces, for example (4,3) or [4,3] as long as you specify this in your answer.
• You should take the input from STDIN and output on STDOUT - if your language does not have these, please use the nearest equivalent.

Test Cases

Input: 1,1

[__]

Input: 2,4

[__][__]
_][__][_
[__][__]
_][__][_

Input: 5,10

[__][__][__][__][__]
_][__][__][__][__][_
[__][__][__][__][__]
_][__][__][__][__][_
[__][__][__][__][__]
_][__][__][__][__][_
[__][__][__][__][__]
_][__][__][__][__][_
[__][__][__][__][__]
_][__][__][__][__][_

Example: Python 3, 65 bytes

This is somewhat golfed but still readable.

w,h=eval(input())
for i in range(h):print(('[__]','_][_')[i%2]*w)

Answer 3

The smallest circles

---

Challenge

This is a variant of the smallest-circle problem, but instead of one circle, you get three. Given a list of coordinates, output three circles such that the following conditions are met:

1. Each input coordinate must be located inside or on the perimeter of a circle.
2. The sum of the radii of all three circles must be minimal.
3. The coordinates and radii of all three circles must be non-negative integers.

You must place all three circles. You may place overlapping circles. A circle with a radius of zero that is directly on top of an input coordinate is considered to be covering that input coordinate.

Input

A list containing between 1 and 1000 pairs of integers, inclusive. Each pair of integers represents an xy-coordinate. Use whatever input format you want to use.

For example, the input...

1,1;1,2;2,2;3,3

... can be drawn like this:

Output

A list of three integer triples. Each triple contains an x coordinate, followed by a y coordinate, followed by a radius. The triples, and the integers within each triple, must be distinguishable from one another. Otherwise, the output format is not important.

Example:

1,1,1;2,2,1;3,3,2

Given this example output, circles would be drawn at (1,1), (2,2), and (3,3). The first two circles would have a radius of 1, and the third would have a radius of 2. The sum of the radii would be 4.

Test case explained

Given the input...

1,1;1,2;2,2;3,3

... you could output...

1,2,1;3,3,0;0,0,0

... or you could output...

1/2/1
3/3/0
0/0/0

The radii sums to 1, and since it is not possible to draw three circles whose radii sum to less than 1 that encompass or touch all four points, this is the correct answer.

---

code-golf math geometry (maybe parsing too)

Answer 4

Make A Rotating Emoji Globe

Your task is to make a globe out of the following characters, with the line being cleared ever 1/3 of a second:

🌍🌎🌏

You must clear the line your emoji globe on it and print the next one every approximate 1/3 of a second.
Output may be to the terminal or elsewhere.
The program must also continue until interrupted on purpose.
Also, your code may not contain the emoji globes themselves, but it may contain Unicode escapes.

---

This is code-golf, so standard loopholes & rules apply.
May the best coder win...

Answer 5

Tron Game

king-of-the-hill grid game

Write a Tron bot!

The aim of the game is to make as many moves on a grid as possible without moving onto a space that has already been occupied in the current game. If your bot is unable to make such a move, it loses the round. The board does not wrap so bots can not go off the side of the arena.

Game IO:

Your bot will be written in python and will create a class that inherits from BotSkeleton. An example test bot is shown below.

from bot_skeleton import BotSkeleton
from typing_hints import PositionDict, Position
from board import Board
from typing import List

import random


class Test(BotSkeleton):
    def make_move(self, board: Board, positions: PositionDict) -> Position:
        self.board = board
        self.position = positions[self.bot_id]
        valid_moves = self.get_valid_moves()
        try:
            return random.choice(valid_moves)
        except IndexError:
            return None

    def get_valid_moves(self) -> List[Position]:
        moves = filter(self.board.position_valid, ((self.position[0]+1, self.position[1]),
                                                   (self.position[0]-1, self.position[1]),
                                                   (self.position[0], self.position[1]+1),
                                                   (self.position[0], self.position[1]-1)))
        return list(moves)

(Type hints are not required but illustrated here to help understanding)

• position is a 2-long tuple containing 2 integers.
• positions is a Dict[bot_id, position]
• board can be indexed with a position.
  • get_random_empty_pos() -> position - returns a empty position at random in the board
  • position_valid(position) -> bool - returns if this move is valid (but not next to the position given)
  • copy() -> List[List[int] - returns a 2d list that can be modifiable of the current board state
  • EMPTY - the id for an empty space
• The value you return must be a position, and must also have a distance of 1 from this, not including diagonals.

Built in attributes for BotSkeleton:

• log - contains a file object that you may write to
• no_bots - the number of bots the game began with
• bot_id - you're bot's id number.

Methods in Board:

• get_random_empty_pos() -> Position - Returns a position at random that is empty
• position_valid(pos: Position) -> bool - returns if a position is inside the board and is currently empty
• copy() -> Board - return a copy of the board that is writable

Tournament structure

• Every bot will get pitted against every other bot in a giant arena
  • That is to say every single bot will be in every battle
  • The size of the arena will be (30, 30). This may be increased depending on number of bots entered.

General rules that I can't find better places for

• Your bot may NOT use any file storage except for write-only access to the log file provided
• Your bot must be written in Python 3. Sorry java people
• You may enter as many bots as you want
• Your bot must not attempt to subvert the game state

I reserve the right to disqualify any bot from the competition

(but shall only do so after telling you I will do so and you not making any changes required)

You may download the controller here

Results:

• Results here

Sandbox notes:

• Should there be a minimum starting distance between players?

Answer 6

Part I: Triangular Manhattan Distance

Part II: Triangular Chebyshev Distance

code-golfhexagonal-gridgeometry

The Chebyshev distance on a regular grid is the number of orthogonal or diagonal steps one needs to take to reach one cell from another. That is, we can move either through the edge of a cell, or through a corner, to a neighbouring cell.

We can define a similar distance on other grids, for example the triangular grid. We can address the individual cells in the grid with the following indexing scheme, where each cell contains an x,y pair:

    ____________________________________...
   /\      /\      /\      /\      /\
  /  \ 1,0/  \ 3,0/  \ 5,0/  \ 7,0/  \
 / 0,0\  / 2,0\  / 4,0\  / 6,0\  / 8,0\
/______\/______\/______\/______\/______\...
\      /\      /\      /\      /\      /
 \ 0,1/  \ 2,1/  \ 4,1/  \ 6,1/  \ 8,1/
  \  / 1,1\  / 3,1\  / 5,1\  / 7,1\  /
   \/______\/______\/______\/______\/___...
   /\      /\      /\      /\      /\
  /  \ 1,2/  \ 3,2/  \ 5,2/  \ 7,2/  \
 / 0,2\  / 2,2\  / 4,2\  / 6,2\  / 8,2\  
/______\/______\/______\/______\/______\...
\      /\      /\      /\      /\      /
 \ 0,3/  \ 2,3/  \ 4,3/  \ 6,3/  \ 8,3/
  \  / 1,3\  / 3,3\  / 5,3\  / 7,3\  /
   \/______\/______\/______\/______\/___...
   /\      /\      /\      /\      /\
  .  .    .  .    .  .    .  .    .  .
 .    .  .    .  .    .  .    .  .    .

Now the Chebyshev distance on this grid is again the minimal number of steps across edges or corners to get from one cell to another. So you can move from 3,1 to any of its 12 neighbours:

2,1 4,1 3,2 (through edges)

3,0 1,2 5,2 (the opposite triangle through corners)

2,0 4,0 1,1
5,1 2,2 4,2 (the other triangles through corners)

For instance, the distance from 2,1 to 7,2 is 3. The shortest path is generally not unique, but one way to make the distance in 3 steps is:

2,1 --> 4,1 --> 5,1 --> 7,2

The Challenge

Given two coordinate pairs x1,y1 and x2,y2 from the above addressing scheme, return the Chebyshev distance between them.

You may assume that all four inputs are non-negative integers, each less than 128. You may take them in any order and arbitrarily grouped (four separate arguments, a list of four integers, two pairs of integers, a 2x2 matrix, ...).

You may write a program or a function and use any of the standard methods of receiving input and providing output.

You may use any programming language, but note that these loopholes are forbidden by default.

This is code-golf, so the shortest valid answer – measured in bytes – wins.

Test Cases

Each test case is given as x1,y1 x2,y2 => result.

1,2 1,2 => 0
0,1 1,1 => 1
1,0 1,1 => 1
2,1 7,2 => 3

Will add more test cases when I have a reference implementation.

Answer 7

Table parser, code golf

Input

|===========|=============|==============|
|Left align |  Right align| Center align |
|===========|=============|==============|
|This       |         This|     This     |
|-----------|-------------|--------------|
|                column                  |
|-----------|-------------|--------------|
|will       |                            |
|-----------|          will be           |
|be         |                            |
|-----------|-------------|--------------|
|left       |        right|    center    |
|-----------|-------------|--------------|
|aligned    |      aligned|   aligned    |
|-----------|-------------|--------------|
|and can be |    vertical-|              |
|multilined | align middle|  as default but a bit long line |
|with <br>  |             |              |
|-----------|-------------|--------------|

Output should be valid HTML. And I am thinking of following requirement specs.

• alignments (left, right, middle)
• border thickness (normal -, |, bold, =,||)
• with table headers or without
• rowspans, colspans
• multiline & vertical-align is always middle

What do you think?

Answer 8

Line up for golf!

Answer 9

This is a proposal adopted by programmer5000. Any feedback before I post it?

Seven-segment usage

I have an old digital clock and I am concerned the individual segments of the digits might run out of magical binary energy or whatever powers them. To know which of the segments on the clock will fail first I want to know what is the percentage of time each segment is lit.

The challenge is to compute the percentage of time any segment on a digital clock is lit.

Input

The input will be in the form X.L, where:

• X is a number from 1 to 4. 1 is the left-most number of the clock, 4 the right-most
• L is a letter from a to g or a number from 1 to 7
• the separator can be changed to fit your needs (no separator is an option)

Output

The output, is a percentage, given with at least 2 figures after the decimal point. It can be rounded or truncated to the closest value if you want to keep a limited number of digits.

Valid outputs: 0.74, 32.47, 7.5 (for 7.50)

Additional stuff

The clock is in 24 hours format (so 22:45 is a valid time).

We consider the clock started working at 0:00 so the challenge is effectively working out what percentage of a complete day a single segment is lit.

The first number is not lit when it is 0.

Lit segments for each number:

• 1: b c
• 2: a b d e g
• 3: a b c d g
• 4: b c f g
• 5: a c d f g
• 6: a c d e f g
• 7: a b c
• 8: a b c d e f g
• 9: a b c d f g
• 0: a b c d e f

Examples

• 1.b => 58.33
• 3.e => 33.33
• 2.d => 70.83
• 4.d => 70.00

Full list of outputs here

Winner

Code golf, most probably, though I am not sure yet this is the best format (I am not too interested in the input parsing and the output formatting, they might be an obstacle to golfing?)

Answer 10

A Game of Knights

In this King of the Hill, you control 10 Knights. You need to surround your enemy before they surround you.

Each Knight has 3 possible actions:

• Dash: Move 3 squares in a cardinal direction. If there is a knight in your path, move as far as you can.
• Leap: Move 2 squares in a cardinal direction. If there is a knight on your destination square, don't move at all.
• Push: Move 1 square in a cardinal direction. If there is a knight on your destination square, and no knight or wall behind him, you both move 1 square.

Each round will have a Planning Phase and then an Action Phase.

Planning:

During the planning phase, players will alternate creating a plan until both players have created 10 plans.

• A plan consists of either an action type or a cardinal direction (not both).
• A plan also includes the knight that will perform the action
• All plans are revealed to both players

Action:

• Actions occur in the same order that they were planned.
• If you planned an action type, you will be able to choose the direction. If you planned a cardinal direction, you will be able to chose the action type you want.

After the action phase, if any knights are on the same location they started at (at the start of the round) are captured and removed from the game. You win by capturing all other knights.

Other info:

• Cardinal means North, East, South, or West
• The board is a 10x10 board. Your knights start as a line at the bottom of the board.
• Walls block movement and cannot be pushed.
• You don't have to plan an action for every knight, and a knight can take multiple actions.
• There are a maximum of 1000 rounds. After those 1000 rounds, the winner is the player with the most knights. (A tie is allowed).
• The starting player for a game is randomized, and that player starts every round.

You have won the game when you opponent cannot make any mobility actions.

Answer 11

The Chroma Key to Success

Answer 12

PPCG VS CR KotH

I am working as fast as I can to get this ready. Please be patient. I have a real job and will attempt to work on this on vacation to the northern states using mobile. I give no promises.

I challenged CR to a KotH challenge. So here is the specs.

Two sides in a arena. 1000x1000. Resources scattered about. A giant area in the center filled with resources. You must build a base and defend your ancient.

You have a few kinds of buildings:

1. Wall: a simple wall that must be broken before walking through. It has 1/2/4/8 health (upgrades). It can be changed into a gate.
2. Gate: a gate that lets the side that made it walk through. Health: 1/2/2/4
3. Turret: Deals 1/1/2/4 damage to the lowest health enemy within a 1/2/4/4 block radius and has 1/1/4/8 health.
4. Resource drop: a place that you can drop resources. Has 2/2/4/6 health.
5. Tower of vision. Gives 10 sight radius with health of five. Costs two resources to build.

Upgrades are 1/2/3/4. The first upgrade is just buying the building.

Gates when transformed stay the same level as the wall they started as, can still be upgraded.

Every bot starts with five health, one damage, and three sight radius. They can upgrade each by four for the cost of 1/2/2/2.

All upgrades take one bot. It takes 1/2/2/3 turns to upgrade an item. The bot must upgrade the item all at once or it must restart and repay the cost. Building a item takes one resource.

Answer 13

Swap the frogs!

Given 2 integers N >= 1, representing left-side frogs, and M >= 1, representing right-side frogs, return all the steps required so that the frogs change sides with the minimum number of steps. The frogs start with one empty spot between the two sides. A frog can jump to the empty space if there is at most 1 frog from either side between the frog and the empty space. A frog can jump either forwards or backwards.

---

An example, with N = 3 and M = 2:

LLL.RR
LL.LRR
LLRL.R
LLRLR.
LLR.RL
L.RLRL
.LRLRL
RL.LRL
RLRL.L
RLR.LL
R.RLLL
RR.LLL

The corresponding output would be (1-indexed):

[3, 5, 6, 4, 2, 1, 3, 5, 4, 2, 3]

Each one is the index of the column that the frog that must jump is before jumping.

Rules

• You may perform I/O in any reasonable format.

Answer 14

Learning your strengths and weaknesses king-of-the-hill

• Fighters have a unique, random Strength (between 1 and 1000)
• When two fighters fight, the stronger one wins.
• Your goal is to accurately guess your fighter's Strength.

Gameplay:

1. We start by randomly ordering all 1000 fighters.

2. Each fighter fights his neighbor (The even fighters fight the fighter 1 above)

3. The fighter is given two pieces of information: His opponent's last guess, and who won the fight. The fighter then guesses his strength.

4. We perform a stable sort based on the guessed strength, and go back to step 2

5. After 10 guesses, the fighter's score is (RealStrength - GuessedStrength)^2. Lower is better.

Other details:

• There will be duplicate bots in a single game.

• A stable sort is a sort that (effectively) uses the past ordering as a tiebreaker. In essence, if players [A,B,C,D] guessed [10,5,10,5] then the new order would be [B,D,A,C]

• Bots aren't allowed to share information between each other, but are allowed to persist information within a single game.

• I will run a large number of games. The exact number will be dependent on how much variation there is. Your final score will be all of your scores summed up.

Answer 15

Can the robotic arm reach itself?

( ͡° ͜ʖ ͡°) title is kinda sketch at the moment

A robotic arm is made up of a set of line segments, each with a positive integer length. Each joint on the robot has two possible positions: straight or 90 degrees clockwise.

Here is a robotic arm with 4 line segments of sizes 4, 2, 3, 2

+---+-+--+-+

Here is the same robot arm with one joint bent

+---+-+
      |
      |
      +
      |
      +

(vertical scale is kinda messed up)

Right now, the robotic arm isn't reaching itself. By bending all of the segments, however, the arm can reach itself.

+X--+
 |  |
 +--+

So, a robotic arm of size [4,2,3,2] can reach itself.

Here is a robotic arm of size [3,1,4,3] that can't reach itself:

+--++---+--+

+
|
|+--+
+---+

Whereas a robotic arm of size [1,1,2,2,3] can reach itself.

++-+-+--+

+
X++
| |
+-+

A robotic arm of size [2,2,3,5,3,4] can also reach itself

a-b-c--d----e--f---g

e--f
|  |
|  |
|a-b
|  g
d--c

Challenge

Given list of numbers, such as [1,2,3,4,5], output a truthy value of the robotic arm can reach itself and a falsey value if it cannot.

Answer 16

Efficient Tab Completion

code-golf string

Many tools that programmers use on a daily basis, like bash and Emacs, have tab completion.

• Pressing Tab in certain situations will attempt to complete the text at the cursor, from a set of possibilities. The term is "completed" by filling in the remaining text.
• For the aforementioned, if there are multiple candidates for completion, you will instead be shown a list of the candidates.
• If there are multiple possibilities but they all start with the same substring/prefix, the rest of that substring will be filled in.

For example, to reach pydoc3, you only have to type

pyd<TAB>3

where Tab is shown as <TAB>. The tab key will insert oc, since all options starting with pyd also start with pydoc _{(in the set below)}.

---

The Challenge

Given a collection of strings called S and a target string called T, figure out the minimum number of keystrokes to reach T, assuming we're using tab completion and S is the set of possibilities.

• Tab completion here is modeled after bash and Emacs, so it is case-sensitive.
• The keystrokes/moves don't matter, only how many. A "keystroke" is:
  • Some character in the string
  • Tab
  • If S is [abc, ab] and T is ab, then either a<TAB> or ab will get there. Tab counts as one keystroke, so the method doesn't matter.
• You may assume terms will only contain alphanumeric characters, underscore, and hyphen ([A-Za-z0-9]_-), for the purpose of this challenge.
• You may assume no strings are empty.
• You may assume S contains T (unsure about this one)
• The input can be taken in whatever format is appropriate for your platform or language (array of strings, string with separators etc.) S and T are considered separate inputs.
  • I/O format is flexible and defaults apply (full program, function etc.)

This is code-golf, so shortest answer in bytes wins.

---

Test Cases

Set                                                 Target         Output
--------------------------------------------------  -------------  ------
[ab, abc]                                           ab             2
[lisp-mode, list-abbrevs, list-packages]            list-packages  5
[heck, hell, help_me, hello, goodbye, hello_world]  hello          5

---

Feedback

• Is anything vague or underspecified?
• Is something too specific or cumbersome?
• Is this too similar to an existing question?
• Should we assume S will always contain T, or require a special case?
• Should something be changed about case-sensitivity? Assume everything is lowercase?
• Any tags I should use?

Answer 17

Existential Golf

Answer 18

Split and recombine a number

This code-golf challenge has two related parts. Your task is to write two functions/programs as per the below specifications. You may share code across your submissions, the submissions may call one another, and you may even submit a single submission which handles both conversions. In the latter case, conversion direction may be determined by whether the input is a single number vs a list, or by an additional consistent second value (not a function) input.

Part 1

Given a floating point number, return a list with one element per digit of its integer part, if any, and if the number is a non-integer, one additional part which is the fractional part. If the number is negative, negate all elements in the output. If the number is zero, return a 1-element list with a zero in it.

When the result list is recombined as per Part 2, it must be precise to within an absolute or relative error of 10⁻¹⁰, whichever is more permissive.

Part 2

Given a list generated as per Part 1, return the number which would have generated that list in Part 1.

When the result number is split as per Part 1, each element must be precise to within an absolute or relative error of 10⁻¹⁰, whichever is more permissive.

Examples

Part 1 <-> Part 2
-123       [-1,-2,-3]
2.71828    [2,0.71828]
-800.6     [-8,0,0,-0.6]
321.7001   [3,2,1,0.7001]
-0.01      [-0.01]
100        [1,0,0]
0          [0]

code-golf number encode decode

Answer 19

Progress: Updated the rules again, and also add the timed function to the bots.

Sylver Coinage KotH king-of-the-hillnumber-theorypython

Sylver Coinage is a 2-player mathematical game that has the following rules:

1. Two players take turns announcing a natural number each time.

2. Each number announced must be unrepresentable as the sum of non-negative multiples of the numbers announced before.

   Eg. if the first three numbers announced are \$\{6, 11, 15\}\$, then you cannot announce any numbers representable as \$6n_1+11n_2+15n_3\$, where \$n_1,n_2,n_3\ge0\$. You can announce, for example, \$16\$, though.

3. The player who announced a number not complying with Rule 2, or the number 1, loses.

Here is a twist -- R. L. Hutchings proved that announcing a prime number as the first play provides a winning strategy for the first player, although the detail of the strategy is not yet known. So I put a restriction here: the first player cannot announce a prime number in the first step. Now the first two numbers will be generated randomly by the driver at the beginning. No more restriction on prime numbers now.

Technical Information

A bot playing the game will have to implement a Python 3 class, extending TimedBot, with two methods: announce() and learn(). announce() should receive a list of numbers (possibly empty) and return a single integer, and learn() should receive two integers (id of the first move and second move) and the complete list of the numbers in the last game played.

Here is a sample implementation. Note: DO NOT use this as your submission -- this sample only serves as a demonstration, and it may announce numbers that violate Rule 2.

class SampleBot(TimedBot):     # must not be changed.
    def __init__(self, id):
        super().__init__()     # must not be changed.
        self.id = id

    def announce(self, list):
        import random
        return random.randint(1, 101)

    def learn(self, first, second, list):
        pass

Test Drive

class TimedBot:
    def __init__(self):
        self.time = 20.0

    def timed(func):
        def f(self, *args):
            import time
            a = time.time()
            b = func(self, *args)
            self.time -= (time.time() - a)
            print(self.time)
            return b
        return f

class SampleBot(TimedBot):
    def __init__(self, id):
        super().__init__()
        self.id = id

    @TimedBot.timed
    def announce(self, list):
        import random
        return random.randint(1, 100001)

    @TimedBot.timed
    def learn(self, first, second, list):
        pass

# very inefficient
def islinearcomb(n, l):
    if len(l):
        for i in range(0, n + 1, l[0]):
            if i == n:
                return [n // l[0]]
            elif len(l) > 1:
                isl = islinearcomb(n - i, l[1:])
                if isl:
                    return [i // l[0]] + isl
    return None

lose = -1
turn = 0
nums = []
bots = [SampleBot(0), SampleBot(1)] # replace with your bots here.

import random
while (len(nums) < 2):
    a, b, c, d = random.randint(1, 10), random.randint(1, 10), random.randint(1, 10), random.randint(1, 10)
    if 2**a * 3**b != 2**c * 3**d and 2**a * 3**b > 100000 and 2**c * 3**d > 100000 and 2**min(a,c) * 3**min(b,d) > 12:
        nums = [2**a * 3**b, 2**c * 3**d]
while lose < 0:
    v = bots[turn].announce(nums)
    print("{0}({1}) announced {2}".format(type(bots[turn]).__name__, bots[turn].id, v))
    w = islinearcomb(v, nums)
    if w:
        str = ""
        for i in range(0, len(nums)):
            if i:
                str += "+"
            str += "{0}*{1}".format(nums[i], w[i] if i < len(w) else 0)
        print("{0}({1}) announced {2} that is equal to {3}".format(type(bots[turn]).__name__, bots[turn].id, v, str))
        lose = turn
    elif v == 1:
        print("{0}({1}) announced 1".format(type(bots[turn]).__name__, bots[turn].id))
        lose = turn
    nums += [v]
    turn = 1 - turn
print("{0}({1}) wins".format(type(bots[1 - lose]).__name__, bots[1 - lose].id))

Restrictions

Each bot will have 20 seconds of time for deciding a move todo: adjustments. Running out time during the move results in a lose, and failing to finish a method within 20 seconds will lead to disqualification and rerun of all 100 rounds with the remaining bots.

Schedule

Submissions will be open until todo: date here. After that 100 complete round-robin rounds will be done. Each pair of bots will compete twice in each round, one with the first bot announcing first, and one with the second bot announcing first. Each win brings 3 points, each draw brings 1 point, and each lose brings no points. The bot with the highest points after 100 rounds wins. The tiebreaker will be as follows:

1. Points got
2. Wins achieved
3. Drawing lots

Answer 20

Interleave Invariance

code-golf number sequence

There is an infinite sequence that does not change when interleaved with the natural numbers. Consider these few terms:

1 1 2 1 3 2 4 1

Interleave them with the naturals:

1   2   3   4   5   6   7   8
  1   1   2   1   3   2   4   1
-------------------------------
1 1 2 1 3 2 4 1 5 3 6 2 7 4 8 1

As you can see, there is no change in the initial eight. Now, this sequence can be extended indefinitely rather easily by repeating this interleave operation. Your task is to choose and implement one of three output formats:

1. Take as input a nonnegative integer n and output the nth term of this sequence, zero- or one-indexed (your choice).

2. Take as input a nonnegative integer n and output the first n terms of this sequence.

3. Output terms in order forever, starting from the beginning.

For options 2 and 3, there must be no numeric characters and at least one non-numeric character between terms; this separator need not be consistent. 1+1=2 would be fine for input 3. Leading and trailing non-numeric characters are allowed.

Here are the first 64 terms. This is OEIS sequence A003602.

1 1 2 1 3 2 4 1 5 3 6 2 7 4 8 1 9 5 10 3 11 6 12 2 13 7 14 4 15 8 16 1 17 9 18 5 19 10 20 3 21 11 22 6 23 12 24 2 25 13 26 7 27 14 28 4 29 15 30 8 31 16 32 1

Your submission can be a program or a function; "input" and "output" are as defined by the community. Standard loopholes are forbidden.

As this is code-golf, the shortest solution (in bytes) wins! Good luck, and happy golfing!

---

Sandboxy Stuff

Am I clear enough on what the sequence is? Any suggestions for rewording?

Is this a duplicate? I've searched for "interleave" and "3602" and found nothing.

Anything else worth mentioning? What thoughts ya gots?

Thanks to Martin Ender for the output formats, taken almost straight from the Kolakoski challenge.

Answer 21

Evaluate C−− expression parsing

Your goal is to a evaluate an expression in "C−−" (not this one) which uses only the characters are C and -. C is an variable holding an integer whose initial value you're given, and the - symbol is used in many ways including as a decrement operator:

• C-- decrements the value stored in C, then evaluates to that value.
• --C evaluates to C, then decrements the value stored in C.
• -expr negates the value of the expression expr.
• expr1-expr2 takes the difference of the two expressions.

Unfortunately, the C−− specification doesn't state how expressions are parsed or in what order parts are evaluated, saying these are "implementation dependent". So, it's up to you. For example, --C---C could be interpreted as -(-(C--)-C) or (--C)-(--C) or others, and each --C might be evaluated before or after other parts of the expression.

Input: A string consisting of C and -, and an integer initial value for C.

The string will be parseable in at least one way. You can take the string as a list of characters, but they must be exactly the characters C and -.

Output: A value this expression could evaluate to.

You don't need to worry about issues with overly large values like overflows or loss of precision.

TODO: test cases

Answer 22

An Auction in St. Petersburg

king-of-the-hill

Setup

Mysterious packages are up for auction today. These boxes are unique in that their values are not known until they are opened, and when they are opened, their values follow a unique distribution:

probability    value
0.5               $2
0.25              $4
0.125             $8
0.0625           $16
1/(2^n)       $(2^n)

In total, there are 100 such packages up for auction, to be sold sequentially. At the start, each bot arrives with $20 in their wallet, and the goal is to walk away with more money than anyone else.

During each round in the auction, each bot simultaneously submits a bid. The bot with the highest bid (ties broken randomly) must pay the value of the second-highest bid, after which that winning bot receives an amount of money corresponding to the value of the opened package. This money can then be "reinvested" in future rounds of the auction.

The auction day ends once all 100 packages have been sold, or when any bot's wallet value exceeds 2^31.

I/O format

As input, your bot receives the following info:

• an array of everyone's current wallet amounts
• the history of past sale prices (the amount paid, not highest amount bid) and winners

As output, your bot returns an integer between 0 and your current wallet amount.

Tournament format

There will be N=large number of game run according to the above format (100 auction rounds each), and the finishing position of the bots will be averaged across games.

Answer 23

Fix my stuttered words

Posted: Fix my stuttered words

Answer 24

Add the quotes code-golf string

Background

There's a terrible problem in my console - the quotes never get included inside the arguments! So, when given this argument:

["abc","def","ghi","jkl"]

it says that the argument is like this:

[abc,def,ghi,jkl]

It would be very nice if you can fix this problem!

Body

Add double-quotes (") in order to surround a word (i.e. something that matches [a-z]+).

[[one, two, three],
[one, two, three],
[one, two, three],
[one, two, three]]

Test cases

[abc,def,ghi,jkl] -> ["abc","def","ghi","jkl"]
this is a test    -> "this" "is" "a" "test"
test              -> "test"
this "one" "contains' "quotations -> "this" ""one"" ""contains"' ""quotations"
But This One Is SpeciaL! -> B"ut" T"his" O"ne" I"s" S"pecia"L!

Rules for the input

• The words are never capitalized.

Answer 25

Is the input Bl lu ur rr ry? code-golf string decision-problem

This is based off this challenge.

Given an input string, check whether the string is blurry.

What's a blurry string?

Take a non-blurrified string abc as an example. You repeat every character of this twice:

aabbcc

And then insert spaces at every odd-even index.

a ab bc c

Then, remove the preceding 2 and succeeding 2 extra characters.

ab bc

As an example, all of these strings are blurry (the empty line stands for an empty string):

"a"   ->
"ab"  ->ab
"abc" ->ab bc
"abcd"->ab bc cd
...

Specification

• The input string consists purely of printable ASCII characters. The only whitespace it will contain is the space character.
• You don't have to remove extra characters before the check.
• Your output can consist of any trailing whitespace, as long as it's possible to tell a truthy result from a falsy result.

Test cases

Here is a program I use to check my test cases.

""          -> True
"ab"        -> True
"ab bc"     -> True
"ab bc cd"  -> True
" b bc cd"  -> True
"ab bc c "  -> True
"a   c cd"  -> True

"a"         -> False
"abc"       -> False
"ab  bc  cd"-> False
"ab#bc#cd"  -> False
"abbccd"    -> False
"a ab bc cd"-> False
"a a ab b b"-> False
"ba cb dc"  -> False
"ba bc dc"  -> False
"FFaallssee"-> False

Answer 26

Draw a Peano Curve with Slashes

Given a positive integer N, draw the N^th iteration of the Peano Curve, using only slashes and backslashes (and spaces). The curve will be rotated at a 45 degree angle from its usual depiction. Here's an example for the first 3 iterations:

N = 1

 /\
/ /
 / /
 \/

N = 2

       /\
      / /
     / / /\
    /  \/ /
   / /\  / /\
   \/ /  \/ /
 /\  / /\  / /\
/ / / / / / / /
 / / / / / / / /
 \/ /  \/ /  \/
   / /\  / /\
   \/ /  \/ /
     / /\  /
     \/ / /
       / /
       \/

N = 3

                         /\
                        / /
                       / / /\
                      /  \/ /
                     / /\  / /\
                     \/ /  \/ /
                   /\  / /\  / /\
                  / / / / / / / /
                 / / / / / / / / /\
                /  \/ /  \/ /  \/ /
               / /\  / /\  / /\  / /\
               \/ /  \/ /  \/ /  \/ /
             /\  / /\  / /\  / /\  / /\
            / / / / /  \/ / / / / / / /
           / / / / / /\  / / / / / / / /\
          /  \/ /  \/ /  \/ /  \/ /  \/ /
         / /\  / /\  / /\  / /\  / /\  / /\
         \/ /  \/ /  \/ /  \/ /  \/ /  \/ /
       /\  / /\  / /\  / /\  / /\  / /\  / /\
      / /  \/ / / / / / / /  \/ / / / / / / / 
     / / /\  / / / / / / / /\  / / / / / / / /\
    /  \/ /  \/ /  \/ /  \/ /  \/ /  \/ /  \/ /
   / /\  / /\  / /\  / /\  / /\  / /\  / /\  / /\
   \/ /  \/ /  \/ /  \/ /  \/ /  \/ /  \/ /  \/ /
 /\  / /\  / /\  / /\  / /\  / /\  / /\  / /\  / /\
/ / / / / / / / / / / / / / / / / / / / / / / / / /
 / / / / / / / / / / / / / / / / / / / / / / / / / /
 \/ /  \/ /  \/ /  \/ /  \/ /  \/ /  \/ /  \/ /  \/
   / /\  / /\  / /\  / /\  / /\  / /\  / /\  / /\
   \/ /  \/ /  \/ /  \/ /  \/ /  \/ /  \/ /  \/ /
     / /\  / /\  / /\  / /\  / /\  / /\  / /\  /
     \/ / / / / / / /  \/ / / / / / / /  \/ / /
       / / / / / / / /\  / / / / / / / /\  / / 
       \/ /  \/ /  \/ /  \/ /  \/ /  \/ /  \/  
         / /\  / /\  / /\  / /\  / /\  / /\    
         \/ /  \/ /  \/ /  \/ /  \/ /  \/ /    
           / /\  / /\  / /\  / /\  / /\  /     
           \/ / / / / / / /  \/ / / / / /      
             / / / / / / / /\  / / / / /       
             \/ /  \/ /  \/ /  \/ /  \/        
               / /\  / /\  / /\  / /\          
               \/ /  \/ /  \/ /  \/ /         
                 / /\  / /\  / /\  /
                 \/ / / / / / / / /
                   / / / / / / / /
                   \/ /  \/ /  \/
                     / /\  / /\
                     \/ /  \/ /
                       / /\  /
                       \/ / /
                         / /
                         \/

You may optionally mirror this horizontally, vertically, or both if you choose. Leading spaces are clearly required for this. Trailing spaces are optional. This is code-golf, so the shortest code wins.

Answer 27

Score a 1 player game of Carcassonne

Answer 28

Posted: Scoring Quantum Tic-Tac-Toe

Answer 29

Build an alphabetised polyglot

Answer 30

My smart phone

Posted here: My smartphone's phonebook