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) {
        // write code here
        int column = grid.length, line = grid[0].length;
        int ans = 0;
        boolean[][] isVisited = new boolean[column][line];
        for (int i = 0; i < column; i++) {
            for (int j = 0; j < line; j++) {
                if (!isVisited[i][j] && grid[i][j] == '1') {
                    ans++;
                    DFS2(grid, isVisited, i, j);
                }
            }
        }
        return ans;
    }

    public void DFS2(char[][] grid, boolean[][] isVisited, int x, int y) {
        if (x < 0 || x >= grid.length || y < 0 || y >= grid[0].length ||
                grid[x][y] == '0' || isVisited[x][y]) {
            return;
        } else {
            isVisited[x][y] = true;
            DFS2(grid, isVisited, x + 1, y);
            DFS2(grid, isVisited, x - 1, y);
            DFS2(grid, isVisited, x, y + 1);
            DFS2(grid, isVisited, x, y - 1);
        }

    }
}