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Questions tagged [cops-and-robbers]

For challenges which consist of two adversary (and asymmetric) sub-challenges.

3
votes
3answers
214 views

Transformers in Disguise (Robbers' Thread)

The cop's thread is here The robber's task is to find a program of size equal to or less than the cop's program, which, when given an itself as input, produces the same output as the cop's program. ...
10
votes
11answers
397 views

Transformers in Disguise (Cops' Thread)

The robber's thread is here The cops task is to write a function or program that, when given an input of itself, outputs a finite deterministic string. If the program is given a different input, it ...
3
votes
4answers
146 views

Modified Boggle-able Code and Output: CnR Edition (Robbers)

This is the Robbers' thread. Cops' thread is here. Background Boggle is a board game where the players have to find English words on a 4-by-4 board of random alphabets. Words can be constructed by ...
8
votes
9answers
250 views

Modified Boggle-able Code and Output: CnR Edition (Cops)

This is the Cops' thread. Robbers' thread is here. Background Boggle is a board game where the players have to find English words on a 4-by-4 board of random alphabets. Words can be constructed by ...
3
votes
2answers
206 views

Polycops and Robbers (Robbers' Thread)

This is the robbers' thread, the cops' thread is here A polyglot is a program, that without modification, can run in multiple languages. Robbers' Challenge First, find a vulnerable cop's answer, ...
2
votes
5answers
534 views

Polycops and Robbers (Cops' Thread)

This is the cops' thread, the robbers' thread is here A polyglot is a program, that without modification, can run in multiple languages. Allowed languages Any language that was made before the ...
30
votes
16answers
2k views

Overlapping Polyglots

Unlike many C&R challenges, this does not require a separate robbers post; the goal of the robbers is to crack the previous answer and then post a new one as a cop. As answerers, you will write a ...
12
votes
14answers
1k views

Hardcoding the Cops and Robbers (Robbers)

This is a cops-and-robbers challenge. The Cops' thread to this challenge is here An interesting question to think about is the following: If I have a sequence of numbers how many of them do I have ...
28
votes
18answers
2k views

Hardcoding the Cops and Robbers (Cops)

This is a cops-and-robbers challenge. The robbers' thread is here. An interesting question to think about is the following: If I have a sequence of numbers how many of them do I have to provide ...
8
votes
6answers
239 views

Golfing Chain (Robbers' Thread)

This is a Cops and Robbers challenge. For the Cops' thread, go here. The Cops have three tasks. 1) Pick a sequence from the OEIS. 2) Pick a language (this is suggested to be a golflang, but doesn'...
13
votes
6answers
335 views

Golfing Chain (Cops' Thread)

This is a Cops and Robbers challenge. For the Robbers' thread, go here. The Cops have three tasks. 1) Pick a sequence from the OEIS. 2) Pick a language (this is suggested to be a golflang, but ...
5
votes
1answer
226 views

Escape from the tarpit (Robbers)

This is a cops-and-robbers challenge based around defining languages and proving they are Turing complete. This is the robbers' thread. The cops' thread is here. Robbers The cops will post ...
7
votes
1answer
394 views

Escape from the tarpit (Cops)

This is a cops-and-robbers challenge based around defining languages and proving they are Turing complete. This is the cops' thread. The robbers' thread is here. Cops As a cop, you will prepare two ...
4
votes
10answers
437 views

This challenge is about recursion (Robbers' thread)

Robbers thread In this thread, your task is to find a non-recursive solution which produces the same integer series of a submission not marked as 'safe' in the Cops' thread. Challenge synopsis In ...
16
votes
12answers
712 views

This challenge is about recursion (Cops' thread)

Cops' thread In this thread, your task is to make a recursion-based program/function to generate any integer series. Robbers will try and find a shorter non-recursive solution over in the Robbers' ...
9
votes
5answers
613 views

Abstract Rewriting Challenge (Robbers)

This is a somewhat proof-golf-like cops-and-robbers challenge. This is the robbers' thread; the cops' thread is here. Robbers The cops will post abstract rewriting systems. Your task is to crack ...
25
votes
10answers
912 views

Abstract Rewriting Challenge (Cops)

This is a somewhat proof-golf-like cops-and-robbers challenge. This is the cops' thread; the robbers' thread is here. Cops Your task is to define an abstract rewriting system in which the ...
30
votes
126answers
8k views

The Programming Language Quiz, Mark II - Robbers

Cops challenge The Robbers' Challenge Find a vulnerable answer. That is, an answer which hasn't been cracked yet and which isn't safe yet either. Crack it by figuring out its language. That is, find ...
61
votes
161answers
14k views

The Programming Language Quiz, Mark II - Cops

A repost of this challenge. Meta discussion. Sandbox post. Body of the question similar to the original Robber's challenge This cops and robbers is now (08/03/2018) closed to further competing cop ...
10
votes
14answers
679 views

Cops and Robbers: Redacted Primality (Robbers' Thread)

This is the robbers' thread. The cops' thread is here. Your challenge is to take an uncracked submission from the cops' thread and try to find the original unredacted program. Please comment on the ...
19
votes
29answers
1k views

Cops and Robbers: Redacted Primality (Cops' Thread)

This challenge was originally sandboxed by Magic Octopus Urn; I adopted and posted it with his permission. This is the cops' thread. The robbers' thread is here. The challenge Step One: Write a ...
6
votes
5answers
210 views

Riffle shuffle a string - Robbers

Cops post A riffle shuffle is a way of shuffling cards where the deck is split into 2 roughly equal sections and the sections are riffled into each other in small groups. This is how to riffle ...
8
votes
9answers
403 views

Riffle shuffle a string - Cops

Robbers post A riffle shuffle is a way of shuffling cards where the deck is split into 2 roughly equal sections and the sections are riffled into each other in small groups. This is how to riffle ...
11
votes
18answers
1k views

Reversed Engineered from Uniqueness (Robber's Thread)

Given the output of the cop's program (o), the byte-count (n) and the number of unique bytes (...
23
votes
46answers
3k views

Reversed Engineered from Uniqueness (Cop's Thread)

Given the output of the cop's program (o), the byte-count (n) and the number of unique bytes (...
11
votes
13answers
1k views

Levenshtein distance & OEIS (Robbers)

This is the Robber post. The Cop post is here. Your task is to take an integer input N and output the Nth digit in the sequence OEIS A002942. The sequence consists of the square numbers written ...
16
votes
15answers
2k views

Levenshtein distance & OEIS (Cops)

This is the Cop post. The Robber post is here. Your task is to take an integer input N and output the Nth digit in the sequence OEIS A002942. The sequence consists of the square numbers written ...
18
votes
20answers
2k views

Find the Needle in the Haystack (Robbers)

This is part of a cops-and-robbers challenge. Go here for the cops' part. The Robbers' Challenge A cop's answer can be cracked by removing any subset of characters from the Haystack program, so that ...
38
votes
22answers
4k views

Hide the Needle in the Haystack (Cops)

This is part of a cops-and-robbers challenge. Go here for the robbers' part. The Cops' Challenge You should write a program or function in a language of your choice, which outputs the string ...
3
votes
6answers
491 views

The greedy regex (cops)

This is the cops' post. The robbers' is here. You make a program and a regex. For most inputs, one of the following happens: the regex doesn't match, and the program returns a falsey value the ...
0
votes
4answers
357 views

The greedy regex (robbers)

This is the robbers' post. The cops' is here. Your challenge is to take a cop's post and find an input that the regex matches but the program returns a falsey value. Once you have cracked a cop's ...
7
votes
15answers
2k views

I'm thinking of a number (Robber's thread)

Cop's thread here In this cops-and-robbers challenge cops will think of a positive integer. They will then write a program or function that outputs one value when provided the number as input and ...
32
votes
26answers
4k views

I'm thinking of a number (Cop's Thread)

Robber's Thread here In this cops-and-robbers challenge cops will think of a positive integer. They will then write a program or function that outputs one value when provided the number as input and ...
11
votes
35answers
3k views

“Hello, World!” (Robbers' thread)

This is the robbers' thread. The cops' thread is here. Your challenge is to take an uncracked submission from the cops' thread and find, for what input or inputs, the program will print ...
16
votes
35answers
4k views

“Hello, World!” (Cops' thread)

This is the cops' thread. The robbers' thread is here. Your challenge is to write a program or function that, with a certain input, prints the exact string ...
12
votes
13answers
1k views

Solving Secret Swapping Sequences

This is a cops-and-robbers challenge, the cops thread can be found here. This is the robbers thread, your job here is to take submissions on the cops thread and try to find the hidden sequences. If ...
20
votes
14answers
1k views

Seeking Secret Swapping Sequences

This is a cops-and-robbers challenge, the robbers thread can be found here. Your task is to write some code that outputs an OEIS sequence, and contains the name of the sequence in the code (...
15
votes
62answers
2k views

Restricted mini challenges Robbers Thread

Cops thread Your task as robbers is to find cops solutions and write a program in the language provided that computes the nth term of the sequence using only the bytes in the provided set. The ...
33
votes
69answers
3k views

Restricted mini challenges Cop's Thread

Robber's thread Your task as cops is to select three things: A programming language An OEIS sequence A byte set You are then to secretly write a program in that language that computes the nth term ...
45
votes
136answers
12k views

Will it halt? (Robbers)

This is the robbers' thread. The cops' thread is here. Your challenge is to crack a cop's submission by finding an input that makes it halt. You don't have to find out why, or all inputs that make it ...
90
votes
107answers
15k views

Will it halt? (Cops)

This is the cops' thread. The robbers' thread is here. Your challenge is to make a program that runs forever without halting1, unless it gets a particular input or inputs2. If it receives that input, ...
18
votes
5answers
622 views

Codebreakers and Codewriters

Let's say you have some text, and you want it to send it to your friend, but you don't want anyone else to read it. That probably means you want to encrypt it so that only you and your friend can ...
30
votes
46answers
8k views

Make your language *mostly* unusable (Robber's thread)

Inspired by this comment... Thanks to users Step Hen, Wheat-Wizard, and Dennis for helping my solidify the specification of this challenge before posting it! This is the Robber's thread! For the ...
60
votes
46answers
11k views

Make your language *mostly* unusable! (Cops' thread)

Inspired by this comment... Thanks to users Step Hen, Wheat-Wizard, and Dennis for helping my solidify the specification of this challenge before posting it! This is the Cops' thread. For the ...
11
votes
1answer
287 views

Cyclic Polyglot Challenge (Cops)

Cyclic Polyglot Challenge This is the cops thread. You can find the robbers thread here. Cyclic Polyglot A N-element cyclic polyglot is a complete program that can be run in N different languages. ...
7
votes
1answer
184 views

Cyclic Polyglot Challenge (Robbers)

Cyclic Polyglot Challenge This is the robbers thread. You can find the cops thread here. Cyclic Polyglot A N-element cyclic polyglot is a complete program that can be run in N different languages. ...
5
votes
7answers
506 views

Stealing sequences: Robbers

This is cops-and-robbers. This is the Robbers thread. For the cops thread, go here. I've noticed a number of OEIS challenges since I joined the site. It seems only fair that we have a cops-and-...
10
votes
6answers
501 views

Stealing sequences: Cops

This is cops-and-robbers. This is the Cops thread. For the robbers thread, go here. I've noticed a number of OEIS (On-line Encyclopedia of Integer Sequences) challenges since I joined the site. It ...
9
votes
17answers
756 views

Cheapo Enigma machine (Robbers)

For cops' post, Cheapo Enigma machine (Cops) A robber's submission consists of a program/function that accepts the output of a cop's code and returns the input for all the outputs provided by that ...
16
votes
15answers
1k views

Cheapo Enigma machine (Cops)

For robbers' post, Cheapo Enigma machine (Robbers) A cop's submission will consist of a program/function that accepts a single byte of data and return a single byte of data. Every possible input must ...