Leetcode Largest Rectangle in Histogram

时间：2014-06-27 23:01:16 阅读：259 评论：0 收藏：0 [点我收藏+]

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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.

参考http://www.geeksforgeeks.org/largest-rectangle-under-histogram/，一般方法如下面代码所示

int largestRectangleArea(vector<int> &height) {
    int maxarea = 0, index = 0, n = height.size();
    stack<int> s;
    while(index < n){
        if(s.empty() || height[s.top()] <= height[index]) s.push(index++);
        else{
            int topIndex = s.top();s.pop();
            int  topOfArea = height[topIndex]*(s.empty() ? index : index-s.top()-1);
            maxarea  = max(topOfArea,maxarea);
        }
    }
    while(!s.empty()){
        int topIndex = s.top();s.pop();
        int  topOfArea = height[topIndex]*(s.empty() ? index : index-s.top()-1);
        maxarea  = max(topOfArea,maxarea);
    }
    return maxarea;    
}