200. 岛屿数量 + dfs

200. 岛屿数量

LeetCode_200

题目描述

代码实现

class Solution {
    int[][] direction = {{-1, 0}, {1, 0}, {0, 1}, {0, -1}};
    int m, n;
    public int numIslands(char[][] grid) {
        m = grid.length;
        n = grid[0].length;
        int cnt = 0;
        for(int i=0; i<m; i++){
            for(int j=0; j < n; j++){
                if(grid[i][j] == '1'){
                    cnt++;
                    grid[i][j] = '0';
                    dfs(i, j, grid);
                }
            }
        }
        return cnt;
    }
    public void dfs(int x, int y, char[][] grid){
        //遍历四个方向
        for(int i=0; i<4; i++){
            int dx = x + direction[i][0];
            int dy = y + direction[i][1];
            if(dx >=0 && dx <m && dy >= 0 && dy < n && grid[dx][dy] == '1'){
                grid[dx][dy] = '0';
                dfs(dx, dy, grid);
            }
        }
    }
}