Maximal Square
Given a binary matrix, find out the largest size square sub-matrix with all 1's and return its area.
Input
matrix: a binary matrix
Output
the area of the largest square in the input matrix
Examples
Example 1:
Input:
matrix = [[1, 0, 1, 0, 0], [1, 0, 1, 1, 1], [1, 1, 1, 1, 0], [1, 0, 0, 1, 0]]
Output: 4
Explanation:
The largest square is of size 2x2 and area 4.