题解 | #岛屿数量#

1、DFS

• flood fill解决

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
     */
    private char[][] grid;
    private int m;
    private int n;
    public int solve (char[][] grid) {
        // write code here
        if (grid == null || grid.length == 0 || grid[0].length == 0) {
            return 0;
        }
        this.grid = grid;
        this.n = grid.length;
        this.m = grid[0].length;
        int count = 0;
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                if (grid[i][j] == '1') {
                    count++;
                    dfs(i, j);
                }
            }
        }
        return count;
    }
    private void dfs(int i, int j) {
        if (i < 0 || i >= n || j < 0 || j >= m || grid[i][j] == '0') return;
        grid[i][j] = '0';
        dfs(i + 1, j);
        dfs(i - 1, j);
        dfs(i, j + 1);
        dfs(i, j - 1);
    }
}