leetcode-dfs-695. 岛屿的最大面积

 

class Solution {
public:
    
    int maxAreaOfIsland(vector<vector<int>>& grid) {
        int maxarea = 0;
        int m = grid.size();
        int n = grid[0].size();
        if(m==0||n==0)
            return maxarea;
        for(int i = 0; i < m; i++){
            for(int j = 0; j < n; j++){
                if(grid[i][j] == 1){
                    maxarea = max(maxarea, search(grid,i,j));
                }
            }
        }
        return maxarea;
    }

    int search(vector<vector<int>>& grid,int i, int j){
        int m = grid.size();
        int n = grid[0].size();
        if(i>=m||j>=n||i<0||j<0||grid[i][j]==0)
            return 0;
        grid[i][j] = 0;  // 正好可以标记为0，代表访问过。
        return 1+search(grid,i,j+1)+search(grid,i,j-1)+search(grid,i-1,j)+search(grid,i+1,j);
    }
};