Add Minesweeper solution

Author: blogscot

minesweeper/Cargo.toml

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+[package]
+name = "minesweeper"
+version = "1.1.0"

minesweeper/README.md

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+# Minesweeper
+
+Add the numbers to a minesweeper board.
+
+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.
+
+In this exercise you have to create some code that counts the number of
+mines adjacent to a square and transforms boards like this (where `*`
+indicates a mine):
+
+    +-----+
+    | * * |
+    |  *  |
+    |  *  |
+    |     |
+    +-----+
+
+into this:
+
+    +-----+
+    |1*3*1|
+    |13*31|
+    | 2*2 |
+    | 111 |
+    +-----+
+
+## Rust Installation
+
+Refer to the [exercism help page][help-page] for Rust installation and learning
+resources.
+
+## Writing the Code
+
+Execute the tests with:
+
+```bash
+$ cargo test
+```
+
+All but the first test have been ignored. After you get the first test to
+pass, open the tests source file which is located in the `tests` directory
+and remove the `#[ignore]` flag from the next test and get the tests to pass
+again. Each separate test is a function with `#[test]` flag above it.
+Continue, until you pass every test. 
+
+If you wish to run all tests without editing the tests source file, use:
+
+```bash
+$ cargo test -- --ignored
+```
+
+To run a specific test, for example `some_test`, you can use:
+
+```bash
+$ cargo test some_test
+```
+
+If the specific test is ignored use:
+
+```bash
+$ cargo test some_test -- --ignored
+```
+
+To learn more about Rust tests refer to the [online test documentation][rust-tests]
+
+Make sure to read the [Modules](https://doc.rust-lang.org/book/second-edition/ch07-00-modules.html) chapter if you
+haven't already, it will help you with organizing your files.
+
+## Feedback, Issues, Pull Requests
+
+The [exercism/rust](https://github.com/exercism/rust) repository on GitHub is the home for all of the Rust exercises. If you have feedback about an exercise, or want to help implement new exercises, head over there and create an issue. Members of the rust track team are happy to help!
+
+If you want to know more about Exercism, take a look at the [contribution guide](https://github.com/exercism/docs/blob/master/contributing-to-language-tracks/README.md).
+
+[help-page]: http://exercism.io/languages/rust
+[modules]: https://doc.rust-lang.org/book/second-edition/ch07-00-modules.html
+[cargo]: https://doc.rust-lang.org/book/second-edition/ch14-00-more-about-cargo.html
+[rust-tests]: https://doc.rust-lang.org/book/second-edition/ch11-02-running-tests.html
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

minesweeper/src/lib.rs

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+use std::char;
+
+const ADJACENCIES: [(i8, i8); 8] = [
+  (-1, -1),
+  (-1, 0),
+  (-1, 1),
+  (0, -1),
+  (0, 1),
+  (1, -1),
+  (1, 0),
+  (1, 1),
+];
+
+pub fn annotate(input: &[&str]) -> Vec<String> {
+  if input.is_empty() {
+    return vec![];
+  }
+  let board = Board::new(input);
+  board
+    .data
+    .iter()
+    .enumerate()
+    .map(|(pos_0, row)| {
+      row
+        .iter()
+        .enumerate()
+        .map(|(pos_1, elem)| {
+          if *elem != '*' {
+            let count = board.neighbours((pos_0 as u8, pos_1 as u8));
+            if count > 0 {
+              char::from_digit(u32::from(count), 10).unwrap()
+            } else {
+              ' '
+            }
+          } else {
+            *elem
+          }
+        })
+        .collect::<String>()
+    })
+    .collect()
+}
+
+#[derive(Debug)]
+struct Board {
+  width: u8,
+  height: u8,
+  data: Vec<Vec<char>>,
+}
+
+impl Board {
+  fn new(input: &[&str]) -> Self {
+    let data = input
+      .into_iter()
+      .map(|row| row.chars().collect::<Vec<_>>())
+      .collect::<Vec<_>>();
+    let height = data.len() as u8;
+    let width = data[0].len() as u8;
+    Board {
+      width,
+      height,
+      data,
+    }
+  }
+  fn neighbours(&self, position: (u8, u8)) -> u8 {
+    let position = (position.0 as i8, position.1 as i8);
+    ADJACENCIES
+      .iter()
+      .map(|adjacent| (position.0 + adjacent.0, position.1 + adjacent.1))
+      .filter(|neighbour| {
+        neighbour.0 >= 0
+          && neighbour.1 >= 0
+          && neighbour.0 < self.height as i8
+          && neighbour.1 < self.width as i8
+      })
+      .fold(0, |acc, pos| {
+        if self.data[pos.0 as usize][pos.1 as usize] == '*' {
+          acc + 1
+        } else {
+          acc
+        }
+      })
+  }
+}

minesweeper/tests/minesweeper.rs

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+extern crate minesweeper;
+
+use minesweeper::annotate;
+
+fn remove_annotations(board: &[&str]) -> Vec<String> {
+  board.iter().map(|r| remove_annotations_in_row(r)).collect()
+}
+
+fn remove_annotations_in_row(row: &str) -> String {
+  row
+    .chars()
+    .map(|ch| match ch {
+      '*' => '*',
+      _ => ' ',
+    })
+    .collect()
+}
+
+fn run_test(test_case: &[&str]) {
+  let cleaned = remove_annotations(test_case);
+  let cleaned_strs = cleaned.iter().map(|r| &r[..]).collect::<Vec<_>>();
+  let expected = test_case.iter().map(|&r| r.to_string()).collect::<Vec<_>>();
+  assert_eq!(expected, annotate(&cleaned_strs));
+}
+
+#[test]
+fn no_rows() {
+  run_test(&[]);
+}
+
+#[test]
+fn no_columns() {
+  run_test(&[""]);
+}
+
+#[test]
+fn no_mines() {
+  run_test(&["   ", "   ", "   "]);
+}
+
+#[test]
+fn board_with_only_mines() {
+  run_test(&["***", "***", "***"]);
+}
+
+#[test]
+fn mine_surrounded_by_spaces() {
+  run_test(&["111", "1*1", "111"]);
+}
+
+#[test]
+fn space_surrounded_by_mines() {
+  run_test(&["***", "*8*", "***"]);
+}
+
+#[test]
+fn horizontal_line() {
+  run_test(&["1*2*1"]);
+}
+
+#[test]
+fn horizontal_line_mines_at_edges() {
+  run_test(&["*1 1*"]);
+}
+
+#[test]
+fn vertical_line() {
+  run_test(&["1", "*", "2", "*", "1"]);
+}
+
+#[test]
+fn vertical_line_mines_at_edges() {
+  run_test(&["*", "1", " ", "1", "*"]);
+}
+
+#[test]
+fn cross() {
+  run_test(&[" 2*2 ", "25*52", "*****", "25*52", " 2*2 "]);
+}
+
+#[test]
+fn large_board() {
+  run_test(&["1*22*1", "12*322", " 123*2", "112*4*", "1*22*2", "111111"]);
+}