LeetCode 200. Number of Islands

Problem Statement

use std::collections::HashMap;

impl Solution {
    fn dfs(grid: &mut Vec<Vec<char>>, x: i32, y: i32) {
        let (m, n) = (grid.len(), grid[0].len());
        let (dx, dy) = ([1, -1, 0, 0], [0, 0, 1, -1]);
        for i in 0..4 {
            let (xx, yy) = (x + dx[i], y + dy[i]);
            if xx < 0 || xx >= m as i32 || yy < 0 || yy >= n as i32 ||
                grid[xx as usize][yy as usize] == '0' {
                continue;
            }
            grid[xx as usize][yy as usize] = '0';
            Self::dfs(grid, xx, yy);
        }
    }
    pub fn num_islands(grid: Vec<Vec<char>>) -> i32 {
        if grid.is_empty() {
            return 0;
        }
        let mut g = grid.clone();
        let (m, n, mut ans) = (grid.len(), grid[0].len(), 0);
        
        for i in 0..m {
            for j in 0..n {
                if g[i][j] == '1' {
                    ans += 1;
                    Self::dfs(&mut g, i as i32, j as i32);
                }
            }
        }

        return ans;
    }
}