https://leetcode.com/problems/maximal-square/description/Given an m x n binary matrix filled with 0's and 1's, find the largest square containing only 1's and return its area. Example 1:Input: matrix = [["1","0","1","0","0"],["1","0","1","1","1"],["1","1","1","1","1"],["1","0","0","1","0"]]Output: 4Example 2:Input: matrix = [["0","1"],["1","0"]]Output: 1Example 3:Input: matrix = [["0"]]Output: 0..