84.直方图中最大矩阵

Largest Rectangle in Histogram

问题描述：

Given n non-negative integers representing the histogram’s bar height where the width of each bar is 1, find the area of largest rectangle in the histogram.



Above is a histogram where width of each bar is 1, given height = [2,1,5,6,2,3].

The largest rectangle is shown in the shaded area, which has area = 10 unit.

参考答案：

class Solution {
public:
int largestRectangleArea(vector<int>& heights) {
stack<int> s;
int i = 0;
int maxarea = 0;

while (i < heights.size()) {
if (s.empty() || heights[i] >= heights[s.top()])
s.push(i++);
else {
int h = heights[s.top()];
s.pop();
int w = s.empty() ? i : i-s.top()-1;

maxarea = max(maxarea, h*w);
}
}

while (!s.empty()) {
int h = heights[s.top()];
s.pop();
int w = s.empty() ? i : i-s.top()-1;
maxarea = max(maxarea, h*w);
}

return maxarea;
}
};

性能：