完结！撒花！

LeetCode 84.柱状图中最大的矩形

题目链接：

LeetCode 84.柱状图中最大的矩形

代码：

class Solution {
public:
    int largestRectangleArea(vector<int>& heights) {
        heights.insert(heights.begin(),0);
        heights.push_back(0);
        int size = heights.size();
        stack<int>st;
        int result = 0;
        st.push(0);
        for(int i=1;i<size;i++){
            if(heights[i]>=heights[st.top()]) st.push(i);
            else{
                while(!st.empty() && heights[i]<heights[st.top()]){
                    int mid = st.top();
                    st.pop();
                    if(!st.empty()){
                        int right = i;
                        int left = st.top();
                        int w = right - left - 1;
                        result = max(result, w*heights[mid]);
                    }
                }
                st.push(i);
            }
        }
        return result;
    }
};