# Description

Given a 2D binary matrix filled with 0’s and 1’s, find the largest square containing all 1’s and return its area.

For example, given the following matrix:

``````1 0 1 0 0
1 0 1 1 1
1 1 1 1 1
1 0 0 1 0
``````

Return 4.

The original problem is here.

The original code is here.

# My Solution

I solve this problem in C++, as below:

``````/*
*Maximal Square
*Author: shuaijiang
*Email: zhaoshuaijiang8@gmail.com
*/
#include<iostream>
#include<vector>
#include<stdlib.h>
using namespace std;

class Solution {
public:
int maximalSquare(vector<vector<char>>& matrix) {
int rowNum = matrix.size();
if(rowNum <= 0)
return 0;
int colNum = matrix[0].size();
vector<int> oneRow(colNum, 0);
vector<vector<int>> dp;
for(int i=0;i<rowNum;i++)
dp.push_back(oneRow);
int sideLength = 0;
// get the maximum side length
for(int i=0;i<rowNum;i++){
for(int j=0;j<colNum;j++){
dp[i][j] = matrix[i][j] - '0';
if(i-1=>0 && j-1=>0 && dp[i][j]>0){
dp[i][j] = min(dp[i-1][j-1], min(dp[i-1][j], dp[i][j-1])) + 1;
}
if(dp[i][j] > sideLength)
sideLength = dp[i][j];
}
}
return sideLength * sideLength;
}
};
``````

# Note

To solve the problem, I use dynamic program and save the maximal side length of the square.