題目：

題解：

class Solution {
public:int maximalRectangle(vector<vector<char>>& matrix) {int m = matrix.size();if (m == 0) {return 0;}int n = matrix[0].size();vector<vector<int>> left(m, vector<int>(n, 0));for (int i = 0; i < m; i++) {for (int j = 0; j < n; j++) {if (matrix[i][j] == '1') {left[i][j] = (j == 0 ? 0: left[i][j - 1]) + 1;}}}int ret = 0;for (int i = 0; i < m; i++) {for (int j = 0; j < n; j++) {if (matrix[i][j] == '0') {continue;}int width = left[i][j];int area = width;for (int k = i - 1; k >= 0; k--) {width = min(width, left[k][j]);area = max(area, (i - k + 1) * width);}ret = max(ret, area);}}return ret;}
};