/*
// Definition for a QuadTree node.
class Node {
public:
    bool val;
    bool isLeaf;
    Node* topLeft;
    Node* topRight;
    Node* bottomLeft;
    Node* bottomRight;
​
    Node() {}
​
    Node(bool _val, bool _isLeaf, Node* _topLeft, Node* _topRight, Node* _bottomLeft, Node* _bottomRight) {
        val = _val;
        isLeaf = _isLeaf;
        topLeft = _topLeft;
        topRight = _topRight;
        bottomLeft = _bottomLeft;
        bottomRight = _bottomRight;
    }
};
*/
class Solution {
public:
    Node* construct(vector<vector<int>>& grid) {
        int N=grid.size();
        if(N==0) return NULL;
        int sum =0;
        for(auto r:grid)
            for(auto c: r)
                sum +=c;
       // cout<<sum<<endl;
        if( sum== N*N || sum ==0) 
        {
          return  new Node(grid[0][0],true, NULL,NULL,NULL,NULL);  
        }
​
        vector<vector<int>> tl(N/2,vector<int>(N/2,0));
        vector<vector<int>> tr(N/2,vector<int>(N/2,0));
        vector<vector<int>> bl(N/2,vector<int>(N/2,0));
        vector<vector<int>> br(N/2,vector<int>(N/2,0));
        bool ftl, ftr,fbl, fbr;
        for(int i=0;i<N/2;i++)
            for(int j=0;j<N/2;j++)
            {
                tl[i][j]=grid[i][j];
                bl[i][j]=grid[i+N/2][j];
                tr[i][j]=grid[i][j+N/2];
                br[i][j]=grid[i+N/2][j+N/2];
            }
​
       return new Node(false,false,construct(tl),construct(tr),construct(bl),construct(br));
    }
};