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

Capsa, a card game KotH!

king-of-the-hillcard-games

Capsa, known by many times, including the name Big Two in English, is a popular card game in East Asia and South East Asia, especially throughout China, Hong Kong, Indonesia, Macau, Malaysia, Singapore and Taiwan. There are many variations and house rules. The rules of this particular variation are thus:

• This game will be played between exactly four bots. The cards are dealt between everyone, so that everyone has 13 cards.
• Rank is ordered with 2s before As as follows: 2, A, K, Q, J, 10, 9, 8, 7, 6, 5, 4, 3, hence, the name Big Two.
• Suits are ordered as follows: Spades, Hearts, Clubs, Diamonds
• Ordering runs rank first then suit. Thus, 7 of Hearts > 7 of Diamonds > 6 of Hearts, the lowest card is the 3 of Diamonds, and the highest, the 2 of Spades

You can play cards in sets of one, two or five cards, (singles, pairs, or five-card poker hands). Each set must always be bigger than the one before.

With singles, play may proceed in this way: 1 3H, 2 4H, 3 5D, 4 5C, 1 10S, 2 Pass, 3 JD, 4 Pass, 1 2S, 3 Pass

Pairs are ordered by the higher suit in the pair. 6C6H is of a lower rank than 6D6S. Play may proceed in this way: 3 3D3C, 4 6D6H, 1 6D6S, 2 JHJS, 3 Pass, 4 ADAC, 1 Pass, 2 Pass

Poker hands are ordered in the following way, from lowest in rank to highest in rank:

• Straight: Five cards that are consecutive in rank, e.g. 6H 7S 8D 9H 10C or JS QH KD AS 2C. Rank is determined by the highest card, with suit used as a tie-breaker.
• Flush: Five cards with the same suit, e.g. 5H 7H 10H QH AH Rank is determined first by suit, then by highest card.
• Full house: A three of a kind with a two of a kind, e.g. JD JS JH 3D 3S. Rank is determined by the triple, without regard for the pair.
• Straight flush: Five cards that are consecutive in rank and are all of the same suit, e.g. 6H 7H 8H 9H 10H. Ranked the same as straights, with suit as a tie-breaker
• Four-of-a-kind: Four cards of the same rank, with any 5th card, e.g. 9D 9C 9H 9S 4S This hand is known as the bomb. Wins any round of poker hands it is played in, unless someone else plays their own bomb.

Any five-card hand that is higher than the previous five-card hand played is eligible. For example, you can play a full house on a straight.

Rules of play:

• At the beginning of the game, the cards are dealt between everyone, so that everyone has 13 cards. The first player is the one that holds the 3 of Diamonds and they must play this card first, whether singly, with another 3 in a pair, or in a poker hand.
• A round begins with the first player playing a single card, a pair or a poker hand. Every other player either respond with the same number of cards (you must play singles on singles, never a pair or a poker hand), or that player passes for that round.
• A player may pass even when they have a playable card, but they must pass if none of their cards are high enough in rank, that is, if they have no playable cards. For example, in a round of poker hands, if you only have a flush as a five-card set, but another player has already played a full house, you must pass, as your flush is too low.
• The round ends when all but one player passes. That last player wins the round and starts the next round.
• The game ends when one player has played all of their cards.

Possible scoring systems:

• Bots are judged by the number of games they win over (TBD) games that they play. So if we have seven bots to test, we'll play them until every bot has played more than (TBD) games.
• Bots are judged by the number of cards they have left at the end of the game. (The winner will obviously have 0 cards at the end of the game).

Here is the link to a preliminary controller and two bots to test against.

Answer 2

Let's Play Unikong

In honor of April Fool's day, we shall have an epic battle to see who can play Unikong best. Or, rather, whose program can play it best.

Goal

Write a program in any language to play the game Unikong. It should seek to try and score as high as possible.

Scoring

Whomever's program has the highest average score, over 10 games wins.

Rules

Standard rules apply. Additionally, your program must actually play the game, not change the score variable by some other means, and you can read the variables from the game to avoid trolls and downvotes, but not modify any variables to make it easier. I will run the tests myself and will use the first 10 runs to calculate the score. Please include any specific instructions needed to run your program.

Notes: This would be my first question, so hopefully I got the format right. Are the rules clear enough? Do I need to clarify anything?

Answer 3

Reverse the lengths

code-golf array-manipulation

---

Specification

In this challenge, your task is to reverse the lengths of an array-of-arrays, while keeping its concatenation intact.

More explicitly, your input is an array of arrays of nonnegative integers, which you may assume to fit in the native int type of your language. The input may be an empty array or an array of empty arrays, or it may contain arrays of different lengths. You can take the input in any reasonable format.

Your output shall be another array of arrays, again in any reasonable format. The concatenation of the output shall be equal to the concatenation of the input, so it contains the same integers in the same order. However, the sequence of lengths in the output shall be the reverse of that of the input.

Example

Consider the input array

A = [[4,10],[0],[],[3,3,2],[1]]

The concatenation of A is

B = [4,10,0,3,3,2,1]

and its length sequence is

C = [2,1,0,3,1]

The correct output is

[[4],[10,0,3],[],[3],[2,1]]

since it's the unique array with concatenation B and length sequence reverse(C).

Rules and scoring

You con write a full program or a function. The lowest byte count wins, and standard loopholes are disallowed.

Test cases

TODO: make more

[] -> []
[[]] -> [[]]
[[],[],[1]] -> [[1],[],[]]
[[1,2],[4,5,6]] -> [[1,2,4],[5,6]]
[[4,10],[0],[],[3,3,2],[1]] -> [[4],[10,0,3],[],[3],[2,1]]

---

Sandbox comments

I'm debating whether I should guarantee that the input is non-empty, and/or only contains non-empty arrays. In some languages (like J), empty arrays make the challenge significantly harder, but on the other hand, I don't want it to be too easy either.

Answer 4

The Secret Handshake

This is based off of this sandbox comment.

king-of-the-hill

---

This is a challenge of secrecy.

The goal of this KOTH is to write a program that is capable of identifying itself amongst a crowd of other programs. In order to do this, you must develop a secret handshake which will be recognized only by other copies of the same program.

A single game involves every program competing at once. There will be five instances of each program in the arena, and the winner will be the first program to correctly identify the four other copies. After a large number of games, the submission with the most victories will be the overall winner.

The Gameflow:

1. Each program receives a number which tells the number of bots in the arena, which is five times the number of submissions. The bots are arranged in a circle, and they are each considered ID #0 from their own perspective, with N-1 being the maximum ID number.
2. Then the game cycle starts. At this point, each bot will be awaiting input.
   1. Your bot will receive input consisting of an ID number and an optional message.
      • For example, 7 hi means that bot #7 said hi to you.
      • If the ID number is 0, then there will not be a message. This would occur if it is your turn but there is no message to receive.
   2. Now, your bot is allowed to output a guess consisting of four ID numbers.
      • If those four numbers are the IDs of your teammates, then your team will win that game.
      • You will receive no confirmation of an incorrect guess.
   3. Next, you must output a message to send. The message will be a destination ID number followed by up to 3* characters. Example messages: 7 4 w 12 #?Q.

*This number is subject to change. Larger messages make it harder to fake a secret handshake. I hope that a very short message forces people to use multi-step handshakes. It might also be interesting to limit it to 1-character messages.

Sandbox Notes

Something that I haven't quite figured out is how the controller program will determine which bot gets to move each turn. I suppose it would be simplest go in order: Each bot has an "unread message queue" and receives/sends one message each turn. The bot immediately after you (ID #1) then moves next.

Alternatively, there could be a set turn order which is unrelated to the ID order, simply to make it impossible for one bot to tell which bot moves next.

Answer 5

Solve the Nonogram!

It is time to embark on a perilous quest to defeat the British Intelligence. The aim of this challenge is to write the shortest code that will solve a Nonogram.

What is a Nonogram?

The rules are simple. You have a grid of squares, which must be either filled in black or left blank. Beside each row of the grid are listed the lengths of the runs of black squares on that row. Above each column are listed the lengths of the runs of black squares in that column. Your aim is to find all black squares. In this puzzle type, the numbers are a form of discrete tomography that measures how many unbroken lines of filled-in squares there are in any given row or column. For example, a clue of "4 8 3" would mean there are sets of four, eight, and three filled squares, in that order, with at least one blank square between successive groups. [1][2]

So the solution to the above Nonogram would be:

Implementation Details

You can chose to represent the Nonogram however you would like and take it as an input in whatever way you deem fit for your language. Same goes for output. The aim of this challenge is to literally just get the job done; if you can solve the monogram with whatever output your program gives, that is valid. One caveat is you can't use an online solver :)

You are, of course, free to use any language you want and since this is code golf, the entries will be sorted in the order: accuracy -> length of code -> speed.

This problem is very algorithmically challenging in that there is no completely efficient solution to it and as such, you won't be penalized for not being able to solve larger ones, although your answer will be heavily rewarded if it is able to handle big cases (see bonus). As a benchmark, my solution works for up to roughly 50x50 within 5-10 mins.

Bonus

I actually learnt about Nonograms from a cryptographic Christmas card released by the British Intelligence here. The first part was basically a massive 25x25 Nonogram. If your solution is able to solve this, you will get kudos :)

To make your life easier in terms of data entry, I have provided how I represented the data for this specific puzzle for your free use. The first 25 lines are the row clues, followed by a '-' separator line, followed by 25 lines of the col clues, followed by a '#' separator line, and then a representation of the grid with the square clues filled in.

7 3 1 1 7
1 1 2 2 1 1
1 3 1 3 1 1 3 1
1 3 1 1 6 1 3 1
1 3 1 5 2 1 3 1
1 1 2 1 1
7 1 1 1 1 1 7
3 3
1 2 3 1 1 3 1 1 2
1 1 3 2 1 1
4 1 4 2 1 2
1 1 1 1 1 4 1 3
2 1 1 1 2 5
3 2 2 6 3 1
1 9 1 1 2 1
2 1 2 2 3 1
3 1 1 1 1 5 1
1 2 2 5
7 1 2 1 1 1 3
1 1 2 1 2 2 1
1 3 1 4 5 1
1 3 1 3 10 2
1 3 1 1 6 6
1 1 2 1 1 2
7 2 1 2 5
-
7 2 1 1 7
1 1 2 2 1 1
1 3 1 3 1 3 1 3 1
1 3 1 1 5 1 3 1
1 3 1 1 4 1 3 1
1 1 1 2 1 1
7 1 1 1 1 1 7
1 1 3
2 1 2 1 8 2 1
2 2 1 2 1 1 1 2
1 7 3 2 1
1 2 3 1 1 1 1 1
4 1 1 2 6
3 3 1 1 1 3 1
1 2 5 2 2
2 2 1 1 1 1 1 2 1
1 3 3 2 1 8 1
6 2 1
7 1 4 1 1 3
1 1 1 1 4
1 3 1 3 7 1
1 3 1 1 1 2 1 1 4
1 3 1 4 3 3
1 1 2 2 2 6 1
7 1 3 2 1 1
#
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 1 1 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 1 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 1 1 0 0 1 0 0 0 1 1 0 0 1 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 1 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 1 0 0 0 0 1 1 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Answer 6

There can be only 1!

Your task is, given a positive integer n, to generate an expression that equals to the number n.

The catch is: you're only allowed the number 1 in the output.

The operators at your disposal are:

• +, -, * and /
• sqrt (as s)
• ceil and floor (as c and f respectively)
• ! (factorial)
  • The factorial, in this case, only works for positive integers.

You are also allowed to stack 1's together, so something like 11 is acceptable in the output. However, they count as the same amount of 1's that's in the number (so 11 counts as 2 1's).

You must also include brackets in the output, so that the expression in the output, when executed through the order of operations, will result in the input.

Examples:

• Input = 24, one possible output = (1+1+1+1)!
• Input = 11, one possible output = 11
• Input = 5, one possible output = c(s((1+1+1+1)!))
  • The ceiling of the square root of 24 is 5.

Rules:

• You are guaranteed that the input is a positive integer from 1 to 2^31-1.
• Your program must work for any positive integer up to 2^31-1, even if they are not tested.
• Your program must finish processing all outputs for all numbers in the set in 1 hour.
• The results for every run of the program must be exactly the same - also, no seeds.
• You are not allowed to have imaginary numbers anywhere in the output (so no s(some negative number)).
• You are also not allowed to have numbers larger than 2^31-1 anywhere in the output, even when they are sqrted or /ed (so no (((1+1+1)!)!)! or ((1+1+1+1)!)!).

Set of Numbers:

945536, 16878234, 32608778, 42017515, 48950830, 51483452, 52970263, 54278649, 63636656, 78817406, 89918907, 90757642, 95364861, 102706605, 113965374, 122448605, 126594161, 148064959, 150735075, 154382918, 172057472, 192280850, 194713795, 207721209, 220946392, 225230299, 227043979, 241011012, 248906099, 249796314, 250546528, 258452706, 276862988, 277140688, 280158490, 286074562, 308946627, 310972897, 322612091, 324445400, 336060042, 346729632, 349428326, 352769482, 363039453, 363851029, 392168304, 401975104, 407890409, 407971913, 425780757, 459441559, 465592122, 475898732, 482826596, 484263150, 506235403, 548951531, 554295842, 580536366, 587051904, 588265985, 588298051, 590968352, 601194306, 607771869, 618578932, 626776380, 667919873, 681786366, 689854904, 692055400, 697665495, 711608194, 734027104, 750869335, 757710567, 759967747, 777616154, 830071127, 833809927, 835873060, 836438554, 836945593, 863728236, 864158514, 871273503, 881615667, 891619600, 897181691, 918159061, 920521050, 924502226, 929983535, 943162304, 950210939, 950214176, 962610357, 974842859, 988572832

(These are 100 random numbers from 1 to 1 billion.)

Scoring System:

Your score is determined like so:

• Your program will be tested against the random numbers in the set.
  • You must provide the output generated using the numbers random numbers in the set (either inside your answer or as a pastebin link).
• Your then have two "scores": A primary score and a secondary score.
  • Your primary score is (no. of 1's in output)*(no. of operators in output). If your primary score is the lowest, you win.
  • Your secondary score is your byte-count, and is only used in the case of a tie-breaker - the person with the lowest byte-count wins.

code-challenge metagolf

Meta:

• Anything that I need to clear up?
• Is this challenge a dupe?

Answer 7

Telegraphy Golf: Decode Baudot Code

Background

In 1870 Émile Baudot invented Baudot Code, a fixed-length character encoding for telegraphy. He designed the code to be entered from a manual keyboard with just five keys; two operated with the left hand and three with the right:

The right index, middle and ring fingers operate the I, II, and III keys, respectively, and the left index and middle fingers operate IV and Ⅴ. (Henceforth I'll use their Western Arabic numerals, i.e. 1, through 5.) Characters are entered as chords. To enter the letter "C," for example, the operator presses the 1, 3, and 4 keys simultaneously, whereupon a rotating brush arm reads each key in sequence and transmits a current or, for keys not depressed, no current. The result is, in modern terms, a 5-bit least-significant-bit-first binary encoding, in which our example, "C," is encoded as 10110.

5 bits??

You might be thinking that 5 bits, which can express at most 32 unique symbols, isn't enough for even all of the English letters and numerals, to say nothing of punctuation. Baudot had a trick up his sleeve, though: His character set is actually two distinct sets: Letters and Figures, and he defined two special codes to switch between them. Letter Shift, which switches to Letters mode, is activated by pressing the 5 key alone (00001), and Figure Shift is activated with the 4 key (00010).

Challenge

Your challenge is to write a program or function that decodes Baudot Code transmissions.

A real transmission would begin with some initialization bits, plus a start and stop bit before and after each character, but we're going to skip those and only worry about the 5 unique bits for each character. Input and output formats are discussed below.

Baudot's Code

There are two different versions of Baudot Code: Continental and U.K. We're going use the U.K. version, which doesn't include characters like "É" from Baudot's native French. We're also going to leave out all of the symbols in the U.K. version that aren't among the printable ASCII characters. You will only have to decode the characters in the table below, all of which are printable ASCII characters except the final three control characters that are explained below the table.

The "Ltr" column shows the characters in Letter mode and "Fig" shows the Figure mode characters:

        Encoding             Encoding
Ltr Fig  12345       Ltr Fig  12345
--- --- --------     --- --- --------
 A   1   10000        P   +   11111
 B   8   00110        Q   /   10111
 C   9   10110        R   -   00111
 D   0   11110        S       00101
 E   2   01000        T       10101
 F       01110        U   4   10100
 G   7   01010        V   '   11101
 H       11010        W   ?   01101
 I       01100        X       01001
 J   6   10010        Y   3   00100
 K   (   10011        Z   :   11001
 L   =   11011        -   .   10001
 M   )   01011        ER  ER  00011
 N       01111        SP  FS  00010
 O   5   11100        LS  SP  00001
 /       11000

The last three rows in the right column are control characters:

• ER is Erasure. Baudot's telegraphy machines would print an asterisk-like symbol for this character to tell the reader that the preceding character should be ignored, but we're going to be even nicer to the reader and actually omit (do not print) the preceding character. It acts the same in both Letter and Figure mode.

• FS is Figure Shift. This switches the character set from Letters to Figures. If the decoder is already in Figure mode, FS is treated as a Space (ergo SP in the "Ltr" column). When the decoder is in Figure mode it stays in Figure mode until an LS character is received.

• LS is Letter Shift. It switches the character set from Figures to Letters. If the decoder is already in Letter mode, LS is treated as a Space. When in Letter mode the decoder stays in Letter mode until an FS character is received.

The decoder always starts in Letter mode.

Here's an example with Figure Shift, Letter Shift, and Space:

01011 10000 00100 00001 00010 10000 11100 00001 10101 11010
  M     A     Y   LS/SP FS/SP   1     5   LS/SP   T     H

This yields the message MAY 15TH. As you can see, the first 00001 (Letter Shift/Space) character acts as a space, because the decoder is already in Letter mode. The next character, 00010 (Figure Shift/Space) switches the decoder to Figure mode to print 15. Then 00001 appears again, but this time it acts as Letter Shift to put the decoder back in Letter mode.

For your convenience, here are the characters in a format that's perhaps easier to digest in an editor, sorted by code:

A,1,10000|E,2,01000|/,,11000|Y,3,00100|U,4,10100|I,,01100|O,5,11100|SP,FS,00010|J,6,10010|G,7,01010|H,,11010|B,8,00110|C,9,10110|F,,01110|D,0,11110|LS,SP,00001|-,.,10001|X,,01001|Z,:,11001|S,,00101|T,,10101|W,?,01101|V,',11101|ER,ER,00011|K,(,10011|M,),01011|L,=,11011|R,-,00111|Q,/,10111|N,,01111|P,+,11111

Input

Input will be a string, array, or list of bits in least-significant-bit-first order. Each character will be represented by a quintet of 5 bits. Bits may be in any reasonable format, e.g. a binary string, an array of 0s and 1s, a string of "0" and "1" characters, a single very large number, etc., as long as it maps directly to the bits of the transmission.

Every transmission will have at least one printable quintet and at most 255 quintets (printable or otherwise), i.e. 5–1,275 bits inclusive.

The input can contain only the bits of the transmission, with two allowed exceptions: Any number of leading or trailing 0 bits and/or, for string input, a single trailing newline may be added to the transmission. Leading or trailing bits or characters cannot be added before or after each quintet, i.e. you cannot pad each quintet to 8 bits or separate quintets with any additional bits, e.g. "01111\n11100".

Notes & edge cases

1. The transmission will contain only the characters in the "Ltr" and "Fig" columns in the table above. You will never receive e.g. 01110 in Figure mode, because it is absent from the "Fig" column.

2. It is assumed that the decoder will always be in Letter mode at the beginning of a transmission. However, the first character may be an FS character to switch to Figure mode immediately.

3. When the decoder is in Letter mode, it may receive an LS character, and when it is in Figure mode it may receive an FS character. In either event a Space character must be printed (see Output).

4. The ER character will never be the first character in a transmission, nor will it ever immediately follow an LS, FS, or another ER.

5. An FS character may immediately follow an LS character and vice versa.

6. Neither the LS nor FS character will be the last character in any transmission.

7. The / and - characters may be received in either Letter mode (codes 11000 and 10001, respectively) or Figure mode (10111 and 00111).

Output

Output may be in any reasonable format, the most reasonable being ASCII (or UTF-8, for which all of the represented characters are the same as ASCII). Please indicate in your answer if your output is in another encoding or format.

Notes

• The space character (see 3. above) should be an ASCII space (0x20) or your encoding's equivalent, i.e. what you get when you press the space bar.

Winning

This is code golf. The shortest code in bytes wins.

Restrictions

• Standard loopholes are forbidden.

• Trailing spaces and/or a single trailing newline are allowed. Leading spaces or other characters (that are not part of the transmission) are disallowed.

• You may not use any built-in or library functions that decode Baudot Code (or any of its descendants, e.g. Murray Code, ITA-1, etc.).

Test Cases

Input: 001101000010100111101110010101
Output: BAUDOT

Input: 11010010001001100011110111101111100
Output: HELLO

Input: 01011100000010000001000101000011100000011010111010
Output: MAY 15TH

Input: 00010001000001000001011101110011100101010010110101010001111100101
Output: 32 FOOTSTEPS

Input: 10110000110101011100111100001111011010000001101110
Output: GOLF

Input: 000100011000001111100000100010110111001100010110010000111111
Output: 8D =( :P

Input: 0000100001000010000100010001111011111011000011100010001
Output (4 leading spaces):     -/=/-

Answer 8

my first post on here, be gentle ;)

---

Find all anagrams within a text

code-golf

Somehow I stumbled upon an implementation of a school assignment from about a year ago, and after having seen many amazing and mindblowing code-golf solutions on here, I thought it's time I bring my own challenge and see how much you guys can blow my mind again ;)

The assignment

Given a text, find all words that have at least one other word in the text as an anagram (case insensitive). Multiple occurrences of the same word are not counted.

The output shall be grouped by words that are an anagram of each other.

Rules

• How you handle input/output is up to you. Function-parameters, file-io, standard in/out, whatever works the best for you.
• You must be able handle any non-empty input as long as you don't run into language or memory limitations.
• The output does not have any fixed formatting. That means you may put them each group at a line, or put them all at one line but use different delimiters, a 2d array, some other exotic data-structure your language of choice happens to have, as long as it makes reasonable sense, it is considered correct. (This means that for example if you are just writing a function, that function does not need to display the output, it could just provide it as a return-value.) Just keep in mind the requirement that the words that are an anagram of each other should be grouped together.
• The order in which the output appears does not matter. That applies to the order of the groups as well as the order of the words within the group.
• A group of only one word is invalid, since that fails the "have at least one other word in the text as an anagram" requirement. (just omit them from your output ^^)
• Each word should only appear once in the output
• All interpunction characters are stripped away from the word before checking for anagrams. That means that "it's" and "its" are the same word (and thus both are an anagram of "sit"). My sample program at the bottom uses http://en.cppreference.com/w/cpp/string/byte/ispunct as check if a character is an interpuntion character. If your language has such a method, you may use it. Otherwise take the characters from the default C locale as specified on there:

  !"#$%&'()*+,-./:;<=>?@[\]^_`{|}~

• All other characters are part of the word and treated as is, so "a" and "á" are not the same.

Example

Given the following input text (the actual text I was given as example by school :P, no idea where this text is coming from...)

Parts of the world have sunlight for close to 24 hours during summer. Dan went to the north pole to lead an expedition during summer. He had a strap on his head to identify himself as the leader. Dan had to deal with the sun never going down for 42 consecutive days and his leadership strap soon became a blindfold. He wondered what kind of traps lay ahead of him.

the following output would be correct:

• 24, 42
• deal, lead
• and, dan
• parts, strap, traps

Or this would also be correct:

24, 42 | deal, lead | and, dan | parts, strap, traps

This one would not

24, 42 , deal, lead , and, dan , parts, strap, traps

(since the groups are not obvious)

My own (non golfed) version to check

The is the exact program I submitted to school back then. You may use it to check your own results.

Added bonus: If it happens to be that this program has a bug (I haven't found them yet) your submission is allowed to have it as well, since it is used to check the result. (In that case you are of course not required to have said bugs)

#include <string>
#include <iostream>
#include <fstream>
#include <map>
#include <set>
#include <algorithm>
#include <cstring>

void stringRemoveInterpunction(std::string& string);
void stringToLower(std::string& string);
std::string stringToAnagramIdentifier(std::string word);

/**
 * due to use of std::ispunct and std::tolower it may not work for text with non-ascii characters??!
 */
int main(int argc, char* argv[]) {
    if (argc < 2) {
        std::cerr << "usage: " << argv[0] << " <filename>" << std::endl;
        return 1;
    }

    std::ifstream fileStream(argv[1]);
    if (!fileStream) {
        std::cerr << "Could not open file " << argv[1] << std::endl;
        return 2;
    }

    // map to store the anagrams, key is so called "anagram identifier", value is a list of the words.
    std::map<std::string, std::set<std::string>> anagrams;

    // read words separated by whitespace from the file
    for (std::string word; fileStream >> word;) {
        // remove interpunction & convert to lowercase, since casing should be ignored
        stringRemoveInterpunction(word); stringToLower(word);

        // add to anagrams-store
        anagrams[stringToAnagramIdentifier(word)].insert(word);
    }

    // display all the anagrams
    for (auto anagram : anagrams) {
        // skip entries which contains only one item, no anagrams found
        if (anagram.second.size() <= 1) {
            continue;
        }

        // output a comma-separated list of the anagrams
        auto anagramIterator = anagram.second.begin();
        std::cout << *anagramIterator++;
        while (anagramIterator != anagram.second.end()) {
            std::cout << ", " << *anagramIterator++;
        }
        std::cout << std::endl;
    }

    return 0;
}

void stringRemoveInterpunction(std::string& string) {
    string.erase(std::remove_if(string.begin(), string.end(), std::ptr_fun<int, int>(&ispunct)), string.end());
}

void stringToLower(std::string& string) {
    std::transform(string.begin(), string.end(), string.begin(), std::ptr_fun<int, int>(&std::tolower));
}

std::string stringToAnagramIdentifier(std::string word) {
    // sort the characters
    std::sort(word.begin(), word.end());
    return word;
}

---

Sandbox Questions

• Do i need to add other tags, or is just code-golf enough?
• I'm not completely sure about the upper-limit of the input text. My idea was that the code should be able to handle any size input as long as its within the memory-limits of the language. Like you don't have to write "memory optimal code" or something, but also shouldn't asume it is smaller than X. I could also just pick an upper limit of "1 kilobyte" or something to avoid any uncertainty about the requirements I think this is fine now as it is.
• Someone in the comments below asked how to handle special characters like $?() so I took a look at how my "check program" handled that and it strips them away before doing the anagram check. So I added a rule for that, but while writing that I felt it makes it needlessly complicated and I'm considering ditching that rule and altering my check-program to reflect that (but then I cant claim its the exact same anymore :( )
• Any other parts that are not clear?

Answer 9

PPCG Handwriting OCR code-challenge test-battery

(insert logo here once I make it)

Given an image consisting of handwritten text, output the text that is written. The image of the handwritten text will be generated by taking characters from one or more handwriting samples given by PPCG users.

Rules

• You may not hardcode your program to only recognize the samples in the corpus.
• There will be sufficient spacing between characters to avoid ambiguity.
• Only ASCII alphanumeric characters (those matching the regex [A-Za-z0-9], i.e. uppercase and lowercase English letters and digits) will be present in the input.
• Inputs will be formed by concatenating individual characters from the handwriting samples.
• The test cases used for scoring may be modified at any point if I feel it is necessary to do so. Reasons may include but are not limited to: needing more test cases to have a single winner, removing problematic test cases, and fixing errors in test cases.

Aside from the above considerations, there are no guarantees on the appearance of the handwriting, as these are actual handwriting samples and thus can have drastic variances.

Score

Your score will be the number of test cases that are correctly recognized, divided by the total number of test cases. The highest score wins. In the event of a tie, the first submission to reach the high score wins. Additional test cases may be added to break ties.

Handwriting Samples

This Imgur album contains the handwriting samples, as well as the names of the users who contributed them.

---

I've made a chat room for submitting handwriting samples. The more samples I get, the better this challenge will be, so please take a few minutes and submit a sample!

Answer 10

2 Spooky 4 Me

In terms of halloween, some things are just too spooky for me... Feel like we need some serious doots from skeletons to fuel our hallowed weens. So, in the spirit of that end, print the following, exactly as it is shown, if and only if the input does not equal "DOOT" (in all caps ONLY):

               _.---._
             .'       '.
             :)       (:
             \ (@) (@) /
              \   A   /
               )     (
               \"""""/
                '._.'
                 .=.
         .---._.-.=.-._.---.
        / ':-(_.-: :-._)-:' \
       / /' (__.-: :-.__) '\ \
      / /  (___.-' '-.___)  \ \
     / /   (___.-'^'-.___)   \ \
    / /    (___.-'='-.___)    \ \
   / /     (____.'='.____)     \ \
  / /       (___.'='.___)       \ \
 (_.:       '---'.=.'---'       :._)
 :||        __  _.=._  __        ||:
 :||       (  '.-.=.-.'  )       ||:
 :||       \    '.=.'    /       ||:
 :||        \    .=.    /        ||:
 :||       .-'.'-._.-'.'-.       ||:
.:::\      ( ,): O O :(, )      /:::.
|||| '     / /''--'--''\ \     ' ||||
''''      / /           \ \      ''''
         / /             \ \
        / /               \ \
       / /                 \ \
      / /                   \ \
     / /                     \ \
    /.'                       '.\
   (_)'                       '(_)
    \\.                       .//
     \\.                     .//
      \\.                   .//
       \\.                 .//
        \\.               .//
         \\.             .//
          \\.           .//
          ///)         (\\\
        ,///'           '\\\,
       ///'               '\\\
      ""'                   '""

---

However, if the input DOES equal "DOOT", in all caps only, print this instead:

               _.---._
             .'       '.
             :)       (:
             \ (@) (@) /
              \   A   /
               )     (
               \"""""/
                '._.'          ' ''''    _''|
                 .=.       @=====***===::_  |
         .---._.-.=.-._.---. (( \-@|_) )) `.|
        / ':-(_.-: :-._)-:' \ ]--------'"
       / /' (__.-: :-.__) '\ \   ||:
      / /  (___.-' '-.___)  \ \  ||:
     / /   (___.-'^'-.___)   \ \ ||:
    / /    (___.-'='-.___)    \ \||:
   / /     (____.'='.____)     \ ||:
  / /       (___.'='.___)       \||:
 (_.:       '---'.=.'---'       :._)
 :||        __  _.=._  __       
 :||       (  '.-.=.-.'  )      
 :||       \    '.=.'    /       
 :||        \    .=.    /      
 :||       .-'.'-._.-'.'-.       
.:::\      ( ,): O O :(, )   
|||| '     / /''--'--''\ \    
''''      / /           \ \
         / /             \ \
        / /               \ \
       / /                 \ \
      / /                   \ \
     / /                     \ \
    /.'                       '.\
   (_)'                       '(_)
    \\.                       .//
     \\.                     .//
      \\.                   .//
       \\.                 .//
        \\.               .//
         \\.             .//
          \\.           .//
          ///)         (\\\
        ,///'           '\\\,
       ///'               '\\\
      ""'                   '""

---

Rules

• Trailing newlines and spaces are allowed.
• The design is horizontally symmetric, if you find inconsistencies let me know.

---

Doot it up, and enjoy!

code-golfascii-artkolmogrov-complexity

---

(Yes, I'm going to make it more official when posting on the actual SE)

Answer 11

Check equation proofs in a ring

code-golf math logic parsing decision-problem

The recent proof-golf to prove that (-a)×(-a) = a×a attracted a number of faulty submissions, because there wasn't an easy way to verify the proofs. So, let's write some proof checkers.

Input

Your program should take a sequence of strings representing expressions in a ring. Valid expressions consist of:

• Single-lowercase-letter variables (a to z)
• Two constants: the additive identity 0 and multiplicative identity 1
• Compound expressions: (X+Y), (X*Y) and (-X), where X and Y stand for subexpressions. (The parentheses must always be present, and there must be no whitespace.)

Task

Your program should check whether:

• All strings except the first and last represent valid expressions.
• Each expression (after the first) can be obtained from the preceding expression, by substituting one of the ring axioms in the expression exactly once.

Output truthy if these conditions are met. Otherwise, output falsey.

You may assume that the first and last strings in the input are valid expressions. But your program must check the intermediate strings.

The ring axioms

For this challenge, use the following substitution rules (and do not use any others). Substitutions can go both left-to-right and right-to-left.

1. (X+(Y+Z)) = ((X+Y)+Z)

2. (X+0) = X

3. (X+(-X)) = 0

4. (X+Y) = (Y+X)

5. (X*(Y*Z)) = ((X*Y)*Z)

6. (X*1) = X

7. (1*X) = X

8. (X*(Y+Z)) = ((X*Y)+(X*Z))

9. ((X+Y)*Z) = ((X*Z)+(Y*Z))

Scoring

Proof checkers are traditionally small, so that people can review them easily. Therefore, your program should be written in as few bytes as possible.

Meta comments

Is the input format fair for most languages and approaches?

Usually, code-golf problems should not require input validation. However, I thought it would be appropriate behaviour for a proof checker. I think the current spec still accommodates regex-based solutions.

The format for the original challenge also listed which axiom was used for each step. I could include this but I doubt that it improves the challenge much.

Test cases

Valid proofs

(0+a)
(a+0)
a

(a*(-1))
((a*(-1))+0)
((a*(-1))+(a+(-a)))
(((a*(-1))+a)+(-a))
(((a*(-1))+(a*1))+(-a))
((a*((-1)+1))+(-a))
((a*(1+(-1)))+(-a))
((a*0)+(-a))

Invalid proofs

These proofs are missing intermediate steps.

(0+a)
a

(-0)
((-0)+0)
0

((a*0)+(-a))
(0+(-a))

This is simply untrue, so no proof should ever be accepted.

(a*b)
(b*a)

Invalid expressions

Your proof checker should reject if these appear partway through a proof.

a+b

(a+-b)

(a + b)

1+

42

Answer 12

ASCII Stock Exchange answer-chainingcode-challenge

At the ASCII Stock Exchange, each character has a price. If a character is used more often, its price rises, otherwise the price decreases over time.

Initially, each character has price 10. [Meta: Is this too low/high?] After each answer, the prices change as follows:

• Each character that is not used in the answer's code has its price decreased by one, except when the price is already one, in which case it stays one.
• If a character is used n-times, then its price increases by n.

We define the score of a piece of code as the sum of the prices of its characters.

Example

For the sake of simplicity, we only consider characters A, B and C for this example. The challenge itself works with all bytes from \0 to \255. Initially, we have the following prices:

A -> 10, B -> 10, C -> 10

If the code of the first answer is BAAA, then is has a score of 40 (computed by taking the previous character prices into account) and the prices change to

A -> 13, B -> 11, C -> 9

If the next answer is CC, it has a score of 18 and the prices are updated to

A -> 12, B -> 10, C -> 11

The Task

Your objective is to write a program or function which calculates the score of a given piece of code in dependence of a list of previous answers which all influence the initial prices in the way described above.

The goal is to do so while minimizing the submission's score itself in the context of this challenge, that is your submission should be able to calculate its own score by taking a list of all previous submissions and its own source code as input.

The answer with the lowest score in each language wins.

Rules

• You may take a list of strings and a string as input, or require that the string to be scored is the first/last element of the list, or any other reasonable input format.
• You may not answer twice in a row.
• If an answer in language X has already been posted, you may only post another answer in language X if your submission achieves a lower score than the previous answer and the code is not identical.
• For this challenge only major releases of languages are considered their own language (e.g. Java 7 vs. Java 8). If there already is an answer in version A of a language and you have an answer in version B of the language and are in doubt whether version B is different enough from version A to be treated as different language, make sure that your code is not valid in version A.

Answer Format

To avoid having to copy all previous answers in order to calculate your submission's score, the chain will maintain a score calculator on TIO. Click on the link to the calculator in the previous answer and enter your code into the input field to calculate its score. Then add your code as a command-line argument, generate a new link and include it in your answer for the next submission.

If you wrote answer number 42 in Haskell with a score of 100, please format it as

42. Haskell, score 100

 <code>

TIO-Link, explanation, ...

Score calculator for next answer

Test Cases

These test cases are in the format list of strings, string to score -> result.

[], "BAAA" -> 40
["BAAA"], "CC" -> 18
["abc"], "abc" -> 33
["ab12", "aa22", "31a"], "ac23" -> 42
["a","b","c","d","e","f","g","h","i","j"], "123" -> 3

---

Meta

• Any idea what could be a good initial price? I picked the number 10 rather arbitrarily.
• Letting the cost of unused characters decrease until 0 might lead to score 0 answers. Do you think this is a problem and the minimum cost should be 1? Minimum changed to 1.
• I'm unsure what range of characters is a sensible choice. Limiting answers to printable ASCII plus white space would make things easier but also exclude a lot of languages. Another possibility would be to allow the whole byte range from \0 to \255. Then also golfing languages could participate, albeit to score them they would need to be converted to their byte form which usually contains a lot of unprintable characters. The score calculator is able to handle unprintables, but I don't know how to insert them into the text fields on TIO. All bytes from \0 to '\255' are allowed.
• Is the winning criterion suitable for answer chaining?
• A leader board snippet would be nice, but I don't know how to modify the existing ones. If someone could provide such a snippet, I would be very grateful.
• Relevant tags?

Answer 13

Note: If you are seeing this first, you might want to sort by active.

Unhappy numbers ascii art

Draw a square (or a rectangle as close to a square as possible) that represents the cycle of an unhappy number.

[ short description of unhappy numbers here + example ]

[ square formating rules ]

Input

Unhappy integer.

Output

ASCII art.

Example

Input:
4
Output:
 4 -  16 - 37 
20         58
42 - 145 - 89

Answer 14

Tower Builder king-of-the-hill

The king is coming to visit! Your city is competing with another neighboring city to attract his attention.

Each player owns their own tower within a city full of other players. Each turn you place 1 blocks on your tower or another tower in your city.

After 100 turns, the king will only visit the city with the highest tower. If he visits your city, then you will gain points equal to the number of blocks in your personal tower. In the case of a tie, neither city is visited.

Games include all players, and each game will randomly arrange players into cities. Your score is the total score across all games.

• Player identifiers are randomly generated at the start of the tournament, but are consistent from game to game.
• In addition, contrary to past KoTHs: I allow saving state from game to game (but not between tournaments)
• You will always have complete information, including:
  • The size of everybody's towers (including the other city)
  • The actions players have taken
  • The current score of all players

Answer 15

Chess ASCII Art, Knight

In honor of the world chess championship, in the shortest possible program, output the following ASCII art piece

      ,....,
   ,::::::<
  ,::/^\"``.
 ,::/, `   e`.
,::; |        '.
,::|  \___,-.  c)
;::|     \   '-'
;::|      \
;::|   _.=`\
`;:|.=` _.=`\
  '|_.=`   __\
   `\_..==`` /
    .'.___.-'.
   /          \
  ('--......--')
  /'--......--'\
   "--......--"

This is a code-golf challenge

Answer 16

Is this checkmate?

Input

A chess position in FEN format. You can assume the input is a valid chess position.

Output

Two distinct consistent outputs for checkmate or not.

Examples

8/8/8/8/8/5BKN/8/7k b - - 93 47
Mate

code-golf chess

Answer 17

Lexicographically earliest valid UTF-8 byte sequence permutation

There are currently 1,114,112 possible Unicode characters (code points). Each character has a unique valid byte sequence in the UTF-8 encoding. Different characters have different length encodings:

• ASCII characters have a 1-byte encoding 00-7F.
• The next 1920 characters have a 2-byte encoding C2 80-DF BF.
• The rest of the BMP has a 3-byte encoding E0 A0 80-ED 9F BF and EE 80 80-EF BF BF.
• The other planes have a 4-byte encoding F0 90 80 80-F4 8F BF BF.

It's possible for two strings (specific non-normalised sequences of Unicode code points) of Unicode to have byte sequences that are permutations of each other in a number of ways:

• One string could simply be a permutation of the other at the Unicode level, e.g. ab (61 62) and ba (62 61).
• UTF-8 continuation bytes could be switched between two characters, e.g. ¡â (C2 A1 C3 A2) and ¢á (C2 A2 C3 A1).
• UTF-8 continuation bytes could be switched within a character, e.g. ᴵ (E1 B4 B5) and ᵴ (E1 B5 B4).

For this challenge I would like you to write a program or function that finds the string whose UTF-8 byte sequence is lexicographically earliest of all such sequences that are permutations of the UTF-8 byte sequence of a given Unicode string.

For example, if your input is ᵴ¢ába (E1 B5 B4 C2 A2 C3 A1 62 61) your output would be ab¡âᴵ (61 62 C2 A1 C3 A2 E1 B4 B5).

Note however that some byte sequences are not valid UTF-8 (e.g. E0 80 A0 which is an overlong encoding for a space) so you need to take care to avoid these.

It would be helpful if your "Try It Online" or similar link includes a footer that helps demonstrate the correctness of your output, where this is not obvious from the I/O format or code.

This is code-golf, so the shortest program or function that breaks no standard loopholes wins!

Answer 18

Compose Fill In The Blanks

Answer 19

Move arrows along a contour

Posted here

ascii codegolf

Answer 20

Posted here

Answer 21

Cliquish Program

Challenge: Write a program that accepts a character (or byte, see additional information) as input. Then:

1. If the character is contained within the source code, output a different character also in your source code.
2. If the character is not contained within the source code, output a different character also not in your source code.

This is a code-golf, so the shortest program (in bytes) wins.

Additional Information

• Your program must consist of at least 2 distinct characters.
• Your program must have at least 2 possible outputs.
• Your program does not have to be deterministic; it may output a character at random (with any distribution), so long as it conforms to the above criteria.
• Your program may optionally take a byte as input instead of characters. If you do, the code page the input is written in must contain at least each distinct byte in the source code, as well as at least two different bytes not in the source code.
• You may take input and give output in any reasonable way. For example, you may take input as a function parameter, a command-line argument, a line from STDIN, a triple-nested array containing a single character, etc. You could output via return value, STDOUT, exit code (if applicable), fax output, etc. The input and output formats must be consistent, however.
• Your output can only consist of the required character, optionally followed by one trailing newline. Prompt information (such as ans =) is exempt from this rule; such unpreventable output is acceptable.

Answer 22

ASCII Maze Unrendering 3000

mazeascii-artcode-golf

Posted

Answer 23

Question link

Answer 24

Almost Illegal Strings

Posted.

Answer 25

Speed of Lobsters

Answer 26

Print random integers until 0

Answer 27

Remove Nth occurrences

Answer 28

Drop some boxes

Answer 29

Non-quining infinite printer

Seems like the title could be better but I'm not sure what to do instead

code-golfquinestring

I have heard that a monkey typing random keys on a typewriter, given infinite time, will eventually type out the entire works of Shakespeare, and in fact type out every possible string of characters of any length. This sounds to me like the basis for a profitable business venture in publishing. Unfortunately, however, as a result of previous failed business ventures, I am legally barred from possessing either monkeys or typewriters, so I'll instead need a program. I want this program to provably generate every possible string of characters, assuming infinite time and memory. Repetition is fine, as is overlap, as long as every possible string appears somewhere in the output. There's a catch, though. I imagine once my business gets off the ground and people realize the potential profits, they might want to get their hands on my program. The trouble is that since I'm outputting every possible string of text, in theory I'll eventually end up outputting the program itself, leaving it open to be stolen. To prevent this, I want the program never to output its own source code. It should still output every other possible string, just not itself (or, obviously, any strings which it is a substring of). Because my funds are currently very tight, I can't afford to pay for more bytes than are necessary, so I'm seeking the shortest possible program that does the job (This is a code-golf challenge, shortest answer in bytes wins). Is it communicated well enough what this challenge is asking for? Should I add a TL;DR and/or a more technical explanation of what's being looked for?

Additional notes:

• I've had enough run-ins with the law in previous ventures, I'd like this one to go smoothly. So no abusing loopholes in the program, please.
• Given that this program is my financial plan for the next infinity years, I'd like some reassurance that it actually does what it's supposed to. Please provide at least a brief explanation of why your code works, since it can't exactly be tested.
• Any character encoding is fine, please specify though. The exception is that your source code must be printable in the encoding you use. Is this a reasonable way to handle this that is fair to all languages?
• No reading your own source, because that makes quine-related holes uncool, and uncoolness does not fit with my businesses' brand persona.

Answer 30

It almost works (C&R)

Cops thread

Robbers thread