LeetCode--Largest Rectangle in Histogram

---恢复内容开始---

class Solution {
public:
    int largestRectangleArea(vector<int> &height) {
        int n = height.size();
        if(n == 0)
        {
            return 0;
        }
        vector<int> leftMax(n);
        vector<int> rightMax(n);
        stack<int> s;
        int i;
        for(i = 0 ; i < n ; ++i)
        {
            leftMax[i] = 0;
            if(i > 0)
            {
                int pre = -1;
                while(!s.empty())
                {
                    int tmp = s.top();
                    if(height[tmp] >= height[i])
                    {
                        s.pop();
                    }
                    else
                    {
                        pre = tmp;
                        break;
                    }
                }
                s.push(i);
                leftMax[i] = i - pre - 1;
            }
            else
            {
                s.push(i);
            }
        }
        stack<int> s1;
        for(i = n-1 ; i >= 0 ; --i)
        {
            rightMax[i] = 0;
            if(i < n-1)
            {
                int next = n;
                while(!s1.empty())
                {
                    int tmp = s1.top();
                    if(height[tmp] >= height[i])
                    {
                        s1.pop();
                    }
                    else
                    {
                        next = tmp;
                        break;
                    }
                }
                s1.push(i);
                rightMax[i] = next - i - 1;
            }
            else
            {
                s1.push(i);
            }
        }
        int res = INT_MIN;
        for(i = 0 ; i < n ; ++i)
        {
            res = max(res,(leftMax[i]+rightMax[i]+1)*height[i]);
        }
        return res;
    }
};

主要目的是记录左边以及右边比当前元素大的元素个数

---恢复内容结束---