题解 | #岛屿数量#

import java.util.*;


public class Solution {
    /**
     * 判断岛屿数量
     * @param grid char字符型二维数组 
     * @return int整型
     */
    public int solve (char[][] grid) {
        int count = 0;

        for (int y = 0; y < grid.length; y++) {
            for (int x = 0; x < grid[0].length; x++) {
                if(grid[y][x] == '0') continue; // 当前不是岛屿
                dfs(grid, x, y); // 当前是岛屿，DFS遍历，把岛屿挖空
                count++;
            }
        }
        return count;
    }

    /**
     * 遍历挖空当前岛屿，并将走过的点设置为0
     * @param grid 地图
     * @param x x坐标
     * @param y y坐标
     */
    private void dfs(char[][] grid, int x, int y){
        if(grid[y][x] == '0') return;
        grid[y][x] = '0';
        if(y>0){
            dfs(grid, x, y-1);
        }
        if(y<grid.length-1){
            dfs(grid, x, y+1);
        }
        if(x>0){
            dfs(grid, x-1, y);
        }
        if(x<grid[0].length-1){
            dfs(grid, x+1, y);
        }
    }
}