Leetcode 84. Largest Rectangle in Histogram (Hard) (cpp)

Leetcode 84. Largest Rectangle in Histogram (Hard) (cpp)

Tag: Array, Stack

Difficulty: Hard

/*

84. Largest Rectangle in Histogram (Hard)

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.

*/
class Solution {
public:
	int largestRectangleArea(vector<int>& heights) {
		stack<int> s;
		int res = 0;
		for (int i = 0; i <= heights.size(); i++) {
			int cur = i == heights.size() ? 0 : heights[i];
			while (!s.empty() && cur <= heights[s.top()]) {
				int height = heights[s.top()];
				s.pop();
				int left = s.empty() ? 0 : s.top() + 1;
				res = max(res, height * (i - left));
			}
			s.push(i);
		}
		return res;
	}
};