. - 力扣（LeetCode）
代码：
//岛屿题目的思想：二维矩阵图的DFS就是，上下左右遍历如果是0或者出界的话就return
//规定的是陆地上下左右是水的话它就是岛屿。当遍历矩阵图中每一个点，
//在调用递归算法之前结果加1,递归算法每次会把一个岛屿全部淹没
class Solution {
public:int numIslands(vector<vector<char>>& grid) {int m = grid.size(); int n = grid[0].size();int res = 0;for(int i = 0;i < m;i++){for(int j = 0;j < n;j++){if(grid[i][j] == '1'){res++;dfs(grid,i,j);}} }return res;}void dfs(vector<vector<char>>& grid,int i,int j){//出界了return if(i < 0 || j < 0 || i >= grid.size() || j >= grid[0].size()){return ;}if(grid[i][j] == '0'){return ;}grid[i][j] = '0';dfs(grid,i - 1,j);dfs(grid,i + 1,j);dfs(grid,i,j - 1);dfs(grid,i,j + 1);}
};
)
