[leetcode] 84. Largest Rectangle in Histogram

Largest Rectangle in Histogram

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.

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

我的代碼

詳細算法解析見上以篇博客只含1最大子矩陣

class Solution {
public:
    int largestRectangleArea(vector<int>& heights) {
        if (heights.empty())
        {
            return 0;
        }
        stack<int> s;
        s.push(0);
        int l,r;
        int max=heights[0], tmpSize;
        int len=heights.size();
        for (int i=1; i<len; i++)
        {
            while (!s.empty() && heights[i] <=  heights[s.top()])
            {
                r=i;
                int e=s.top();
                s.pop();
                l=s.empty()?-1:s.top();
                tmpSize=(r-l-1)*heights[e];
                if (tmpSize > max)
                    max = tmpSize;
            }
            s.push(i);
        }
        while (!s.empty())
        {
            r=len;
            int e=s.top();
            s.pop();
            l=s.empty()?-1:s.top();
            tmpSize=(r-l-1)*heights[e];
            if (tmpSize > max)
                max = tmpSize;
        }
        return max;  
    }
};