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A tag is a keyword or label that categorizes your question with other, similar questions. Using the right tags makes it easier for others to find and answer your question.

This challenge is related to the Python language. Note that challenges that require the answers to be in a specific language are generally discouraged.
139 questions
Problems in geometry or graph theory that involve finding an optimal (e.g. shortest) path, subject to constraints (obstacles).
135 questions
These challenges involve processing pre-existing image files, by altering them in some way, gathering statistics, or other image processing tasks.
133 questions
Problems involving processing of natural languages in a human way. Tasks include interpreting free text, correcting spelling or grammar, understanding pronunciation, etc.
133 questions
Tasks involving writing interpreters for various languages or formalisms.
131 questions
For challenges focusing on the optimization of an aspect not covered by other tags. (not a winning criterion)
131 questions
Chess is a strategic game played with two players on a checkered grid. This tag is for challenges related to chess or any variation on chess.
128 questions
The challenge involves Fibonacci numbers or one of their generalizations.
126 questions
For challenges regarding counting the number of occurrences of some characteristic.
124 questions
Challenges pertaining to a sequence within a larger sequence
119 questions
This challenge is related to the JavaScript language. Note that challenges that require the answers to be in a specific language are generally discouraged.
108 questions
For challenges involving code that runs in multiple programming languages.
107 questions
For challenges where an exact output is not required but some property must still be fulfilled.
106 questions
In a balanced string certain pairs of characters or substrings always appear with the same amount. Often there are additional restrictions that those pairs also have to be ordered. The most common exa…
104 questions
if your challenge is about writing programs that solve puzzles such as Sudoku, Rubik's Cube, Crossword puzzles, etc.
101 questions
Palindromes are words, phrases, representations of numbers or times which read the same in reverse, for example "level", "reviver", "12321", "10:01". See also the [balanced-string] tag.
100 questions
This challenge involves the manipulation of rational numbers, i.e. those which can be represented as a fraction of integers. Do not use this tag if rational numbers are just one of several admissible …
100 questions
Code challenges that involve the use of regular expressions.
97 questions
indicates that the challenge requires answers to use the Internet to retrieve information.
97 questions
Related to compressing or decompressing arbitrary data. Challenges which relate to compressing a single specific input should instead be tagged [kolmogorov-complexity]
96 questions
For challenges where answers are expected to generate code.
93 questions
For challenges with a restriction on the amount of time a submission is allowed to use.
93 questions
For challenges involving unicode.
92 questions
A challenge that involves making a "Hello, World!" program, or other similar strings. It is recommended to avoid using exactly "Hello, World!" as many languages have builtins to print it, trivialising…
89 questions
For challenges involving polynomials, mathematical expressions that consist of variables and coefficients.
89 questions
For challenges which involve card games. This includes playing the game, implementing the game, as well as challenges concerned with individual mechanics and analysis of the game (for instance, comput…
85 questions
For challenges involving the usage and manipulation of the alphabet.
84 questions
Atomic code golf is scored by the number of operations in a specific fragment of a language you define.
84 questions
indicates that the challenge involves converting from one format to another.
79 questions
Challenges with a spec which requires all answers to meet certain time complexity restrictions. This could be specific ("Your answer must be O(n^2) where n is the number of items in the input"), or at…
79 questions
This challenge is related to the BF language. Note that challenges that require the answers to be in a specific language are generally discouraged.
78 questions
Fastest-algorithm competitions are won by the answer with the smallest asymptotic time complexity. For challenges based on actual runtime, use [fastest-code] instead.
78 questions
for challenges involving board games.
77 questions
Challenges relating to the 95 printable ASCII characters (space to ~). Tabs and newlines may be included as well, depending on the challenge.
75 questions
indicates that the challenge involves music, e.g. taking music as input, producing music as output or handling musical notes.
73 questions
For challenges involving bitwise commands or manipulation of numbers at the bit level
73 questions
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