【LeetCode 84. Largest Rectangle in Histogram】

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.

 

Example:

Input: [2,1,5,6,2,3]
Output: 10

Solution1:枚举所有可能构成的矩形，求最大面积（大规模测试用例下超时）

class Solution {
public:
    int largestRectangleArea(vector<int>& heights) {
        int maxArea = 0;
        for(int i = 0; i < heights.size(); i++){
            maxArea = max(maxArea,heights[i]);
            int minH = heights[i];
            for(int j = i+1; j < heights.size(); j++){
                minH = min(minH, heights[j]);
                maxArea = max(maxArea, (j-i+1) * minH);
            }
        }
        return maxArea;
    }
};