题解 | #岛屿数量#

#include <vector>
class Solution {
public:

    void dfs(vector<vector<char>>& grid, int i, int j){
        int n = grid.size(); // 行
        int m = grid[0].size(); // 列
        grid[i][j] = '0';
        if(i - 1 >= 0 && grid[i - 1][j] == '1'){
            dfs(grid, i - 1, j);
        }
        if(i + 1 < n && grid[i + 1][j] == '1'){
            dfs(grid, i + 1, j);
        }
        if(j + 1 < m && grid[i][j + 1] == '1'){
            dfs(grid, i, j + 1);
        }
        if(j - 1 >= 0 && grid[i][j - 1] == '1'){
            dfs(grid, i, j - 1);
        }
    }
    int solve(vector<vector<char>> grid) {
        int n = grid.size();
        if(n == 0) return 0;
        int m = grid[0].size();
        int cnt = 0;
        for(int i = 0; i < n; i ++){
            for(int j = 0; j < m; j ++)
                if(grid[i][j] == '1'){
                    cnt ++;
                    dfs(grid, i, j);
                }
        }
        return cnt;
    }
};