题目：

题解：

class Solution {
public:int maximalSquare(vector<vector<char>>& matrix) {if (matrix.size() == 0 || matrix[0].size() == 0) {return 0;}int maxSide = 0;int rows = matrix.size(), columns = matrix[0].size();vector<vector<int>> dp(rows, vector<int>(columns));for (int i = 0; i < rows; i++) {for (int j = 0; j < columns; j++) {if (matrix[i][j] == '1') {if (i == 0 || j == 0) {dp[i][j] = 1;} else {dp[i][j] = min(min(dp[i - 1][j], dp[i][j - 1]), dp[i - 1][j - 1]) + 1;}maxSide = max(maxSide, dp[i][j]);}}}int maxSquare = maxSide * maxSide;return maxSquare;}
};