# Find the largest square in Matrix (Java)

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:

```
1101
1101
1111

```

Return 4.

Analysis

This problem can be solved by dynamic programming. The changing condition is:
t[i][j] = min(t[i][j-1], t[i-1][j], t[i-1][j-1]) + 1. It means the square formed before this point.

```
public int maximalSquare(char[][] matrix) {
if(matrix==null||matrix.length==0){
return 0;
}

int result=0;
int[][] dp = new int[matrix.length][matrix[0].length];

for(int i=0; i<matrix.length; i++){
dp[i][0]=matrix[i][0]-'0';
result=Math.max(result, dp[i][0]);
}

for(int j=0; j<matrix[0].length; j++){
dp[0][j]=matrix[0][j]-'0';
result=Math.max(result, dp[0][j]);
}

for(int i=1; i<matrix.length; i++){
for(int j=1; j<matrix[0].length; j++){
if(matrix[i][j]=='1'){
int min = Math.min(dp[i-1][j], dp[i][j-1]);
min = Math.min(min, dp[i-1][j-1]);
dp[i][j]=min+1;

result = Math.max(result, min+1);
}else{
dp[i][j]=0;
}
}
}

return result*result;
}

```