<p>Given a <code>m * n</code> matrix of ones and zeros, return how many <strong>square</strong> submatrices have all ones.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> matrix =
[
&nbsp; [0,1,1,1],
&nbsp; [1,1,1,1],
&nbsp; [0,1,1,1]
]
<strong>Output:</strong> 15
<strong>Explanation:</strong> 
There are <strong>10</strong> squares of side 1.
There are <strong>4</strong> squares of side 2.
There is  <strong>1</strong> square of side 3.
Total number of squares = 10 + 4 + 1 = <strong>15</strong>.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> matrix = 
[
  [1,0,1],
  [1,1,0],
  [1,1,0]
]
<strong>Output:</strong> 7
<strong>Explanation:</strong> 
There are <b>6</b> squares of side 1.  
There is <strong>1</strong> square of side 2. 
Total number of squares = 6 + 1 = <b>7</b>.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= arr.length&nbsp;&lt;= 300</code></li>
	<li><code>1 &lt;= arr[0].length&nbsp;&lt;= 300</code></li>
	<li><code>0 &lt;= arr[i][j] &lt;= 1</code></li>
</ul>

class Solution {
public:
    int rec(int i,int j,vector<vector<int>>& matrix,int &cnt,vector<vector<int>>&dp,vector<vector<bool>>&vis){
        if(i>=matrix.size() or j>=matrix[0].size()) return 0;
        if(dp[i][j]!=-1) return dp[i][j];
        int right=rec(i,j+1,matrix,cnt,dp,vis);
        int bottom=rec(i+1,j,matrix,cnt,dp,vis);
        int diagonal=rec(i+1,j+1,matrix,cnt,dp,vis);
        if(matrix[i][j]==1){
            int ans=1+min(right,min(diagonal,bottom));
            if(vis[i][j]==false){
                cnt+=ans;
                vis[i][j]=true;
            }
            return dp[i][j]=ans;
        }
        else return dp[i][j]=0;
    }
    int countSquares(vector<vector<int>>& matrix) {
        int i=0;
        int j=0;
        int cnt=0;
        int n=matrix.size();
        int m=matrix[0].size();
        vector<vector<int>>dp(n+1,vector<int>(m+1,-1));
        vector<vector<bool>>vis(n+1,vector<bool>(m+1,false));
        rec(i,j,matrix,cnt,dp,vis);
        return cnt;
    }
};
29800