题解 | #岛屿数量#

dfs

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 int[][] dir = new int[][]{{0, -1}, {0, 1}, {-1, 0}, {1, 0}};
    public void dfs(char[][] grid, int i, int j, int n, int m) {
        grid[i][j] = '0';
        for (int k = 0; k < 4; k++) {
            int x = i + dir[k][0];
            int y = j + dir[k][1];
            if (0 <= x && x < n && 0<= y && y < m && grid[x][y] == '1') {
                dfs(grid, x, y, n, m);
            }
        }
    }
    public int solve (char[][] grid) {
        int m = grid[0].length;
        int n = grid.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(grid, i, j, n, m);
                }
            }
        }
        return count;
    }
}