题解 | 岛屿数量

import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 判断岛屿数量
     * @param grid char字符型二维数组 
     * @return int整型
     */
    int count = 0;
    int m = 0;
    int n = 0;
    public int solve (char[][] grid) {
        // write code here
        this.m = grid.length;
        this.n = grid[0].length;
        for (int i=0; i<m; i++) {
            for (int j=0; j<n; j++) {
                if (grid[i][j] == '1') {
                    dfs(grid, i, j);
                    count++;
                }
            }
        }
        return count;
    }
    private void dfs(char[][] grid, int i, int j) {
        if (i < 0 || i>= m || j < 0 || j>=n || grid[i][j] == '0') return;
        grid[i][j] = '0';
        dfs(grid, i-1, j); // 上
        dfs(grid, i+1, j); // 下
        dfs(grid, i, j-1); // 左
        dfs(grid, i, j+1); //右
    }
}