求在0-1矩阵中找出面积最大的全1矩阵
Given a 2D binary matrix filled with 0's and 1's, find the largest rectangle containing all ones and return its area.首先，想使用遍历两次的暴力方法解决是不靠谱的，先打消这个念头。
Largest Rectangle in Histogram0，那么当前一唯矩阵置为0，否则加1。
class Solution {public: int largestRectangleArea(vector<int> &h) { stack<int> S; h.push_back(0); int sum = 0; for (int i = 0; i < h.size(); i++) { if (S.empty() || h[i] > h[S.top()]) S.push(i); else { int tmp = S.top(); S.pop(); sum = max(sum, h[tmp]*(S.empty()? i : i-S.top()-1)); i--; } } return sum; } int maximalRectangle(vector<vector<char> > &matrix) { if(matrix.size() == 0 || matrix[0].size() == 0) return 0; int maxArea = 0; vector<int> temp(matrix[0].size(), 0);//用来调用辅助函数的参数向量 for(int i = 0; i < matrix.size(); i++){ for(int j = 0; j < matrix[0].size(); j++){ //在每一行都重置辅助向量 if(matrix[i][j] == '1') temp[j]++; else temp[j] = 0; //断开了，就置零 } int ret = largestRectangleArea(temp); maxArea = ret > maxArea ? ret : maxArea; } return maxArea; } };
