【力扣 062】84. 柱状图中最大的矩形

84. 柱状图中最大的矩形

解法1：

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