Maximum Sum Square SubMatrix

• Time : $O(n^2)$
• Space : $O(n^2)$

int Solution::solve(vector<vector<int> > &A, int B) {
    int n = A.size();
    vector<vector<int>> dp(n + 1, vector<int>(n + 1));
    int res = INT_MIN;
    for(int i = 0; i < n; i++) {
        for(int j = 0; j < n; j++) {
            dp[i+1][j+1] = dp[i][j+1] + dp[i+1][j] - dp[i][j] + A[i][j];
            if(i + 1>= B and j + 1>= B) res = max(res, dp[i+1][j+1] - dp[i+1-B][j+1] - dp[i+1][j+1-B] + dp[i+1-B][j+1-B]);
        }
    }
    return res;
}