73 lines
1.8 KiB
Markdown
73 lines
1.8 KiB
Markdown
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# Minesweeper
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Welcome to Minesweeper on Exercism's Rust Track.
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If you need help running the tests or submitting your code, check out `HELP.md`.
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## Instructions
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Add the mine counts to a completed Minesweeper board.
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Minesweeper is a popular game where the user has to find the mines using numeric hints that indicate how many mines are directly adjacent (horizontally, vertically, diagonally) to a square.
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In this exercise you have to create some code that counts the number of mines adjacent to a given empty square and replaces that square with the count.
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The board is a rectangle composed of blank space (' ') characters.
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A mine is represented by an asterisk (`*`) character.
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If a given space has no adjacent mines at all, leave that square blank.
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## Examples
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For example you may receive a 5 x 4 board like this (empty spaces are represented here with the '·' character for display on screen):
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```text
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·*·*·
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··*··
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··*··
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·····
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```
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And your code will transform it into this:
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```text
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1*3*1
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13*31
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·2*2·
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·111·
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```
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## Performance Hint
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All the inputs and outputs are in ASCII.
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Rust `String`s and `&str` are utf8, so while one might expect `"Hello".chars()` to be simple, it actually has to check each char to see if it's 1, 2, 3 or 4 `u8`s long.
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If we know a `&str` is ASCII then we can call `.as_bytes()` and refer to the underlying data as a `&[u8]` (byte slice).
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Iterating over a slice of ASCII bytes is much quicker as there are no codepoints involved - every ASCII byte is one `u8` long.
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Can you complete the challenge without cloning the input?
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## Source
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### Created by
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- @EduardoBautista
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### Contributed to by
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- @ashleygwilliams
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- @coriolinus
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- @cwhakes
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- @EduardoBautista
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- @efx
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- @ErikSchierboom
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- @ffflorian
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- @IanWhitney
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- @kytrinyx
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- @lutostag
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- @mkantor
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- @nfiles
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- @petertseng
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- @rofrol
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- @stringparser
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- @workingjubilee
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- @xakon
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- @ZapAnton
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