93 lines
2.4 KiB
Rust
93 lines
2.4 KiB
Rust
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use std::collections::{HashSet, VecDeque};
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type Position = (i32, i32);
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type Grid = Vec<Vec<char>>;
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impl Solution {
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fn indices(grid: &Grid) -> impl Iterator<Item = Position> + '_ {
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(0..grid.len() as i32)
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.flat_map(move |y| (0..grid[y as usize].len() as i32).map(move |x| (y, x)))
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}
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fn interesting(grid: &Grid, visited: &HashSet<Position>, p: &Position) -> bool {
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let (max_y, max_x) = (grid.len() as i32, grid[0].len() as i32);
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let &(y, x) = p;
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y >= 0
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&& y < max_y
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&& x >= 0
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&& x < max_x
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&& grid[p.0 as usize][p.1 as usize] != '0'
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&& !visited.contains(p)
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}
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fn bfs(grid: &Grid, visited: &mut HashSet<Position>, pos: Position) {
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let mut queue: VecDeque<Position> = VecDeque::new();
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queue.push_back(pos);
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visited.insert(pos);
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while let Some(p) = queue.pop_front() {
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for d in [-1, 1] {
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for adjacent in [(p.0 + d, p.1), (p.0, p.1 + d)] {
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if Solution::interesting(grid, visited, &adjacent) {
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queue.push_back(adjacent);
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visited.insert(adjacent);
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}
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}
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}
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}
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}
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pub fn num_islands(grid: Grid) -> i32 {
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let mut visited: HashSet<Position> = HashSet::new();
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let mut islands = 0;
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for (y, x) in Solution::indices(&grid) {
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if !Solution::interesting(&grid, &visited, &(y, x)) {
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continue;
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}
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Solution::bfs(&grid, &mut visited, (y, x));
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islands += 1;
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}
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islands
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}
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}
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struct Solution {}
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fn main() {
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println!("Hello World!");
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_example_1() {
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assert_eq!(
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Solution::num_islands(vec![
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vec!['1', '1', '1', '1', '0'],
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vec!['1', '1', '0', '1', '0'],
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vec!['1', '1', '0', '0', '0'],
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vec!['0', '0', '0', '0', '0']
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]),
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1
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);
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}
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#[test]
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fn test_example_2() {
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assert_eq!(
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Solution::num_islands(vec![
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vec!['1', '1', '0', '0', '0'],
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vec!['1', '1', '0', '0', '0'],
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vec!['0', '0', '1', '0', '0'],
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vec!['0', '0', '0', '1', '1']
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]),
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3
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);
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}
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}
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