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.
可参考演示过程
利用一个栈，并在堆栈中维护一个递增的数列，当数组中当前值大于栈顶值时直接将当前值的下标入栈，不然栈顶元素出栈，计算以该元素为高的面积；
int largestRectangleArea(vector<int>& heights) { if (heights.size() == 0)return 0; heights.push_back(-1); stack<int> temp; int index = 0; int res = 0; while (index < heights.size()){ if (temp.empty() || heights[index] >= heights[temp.top()]){ temp.push(index++); } else{ int highindex = temp.top(); temp.pop(); res = max(res, heights[highindex] * (temp.empty() ? index : index - temp.top() - 1)); } } return res; }