LeetCode:Largest Rectangle in Histogram（update）

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.

For example,
Given height = [2,1,5,6,2,3],
return 10.

别人家的巧妙的代码：每次都维护一个递增的栈 比较栈顶与当前元素。如果当前元素小于栈顶元素，则入栈，否则合并现有栈，直至栈顶元素小于当前元素。结尾时

入栈元素为0,重复合并一次。

class Solution {
public:
    int largestRectangleArea(vector<int>& height) {
        
         stack<int> s;
         
         int result=0;
         height.push_back(0);
         
         for(int i=0;i<height.size();i++)
         {
             if(s.empty()||height[s.top()]<height[i])
                s.push(i);
              else{
                
                     int index = s.top(); 
                     s.pop();
                     int width = s.empty() ? i : (i-s.top()-1);
                     result = max(result,height[index] * width);
                     i--;
        
              }
         }
         return result;
        
    }
};