【leetcode】Array——Largest Rectangle in Histogram（84）

題目：

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.

For example,

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

思路：Stack

見鏈接：http://www.geeksforgeeks.org/largest-rectangle-under-histogram/

代碼：

public class Solution {
    public int largestRectangleArea(int[] height) {
        int len = height.length;
        Stack<Integer> s = new Stack<Integer>();
        int maxArea = 0;
        for(int i = 0; i <= len; i++){
            int h = (i == len ? 0 : height[i]);
            if(s.isEmpty() || h >= height[s.peek()]){
                s.push(i);
            }else{
                int tp = s.pop();
                maxArea = Math.max(maxArea, height[tp] * (s.isEmpty() ? i : i - 1 - s.peek()));
                i--;
            }
        }
        return maxArea;
    }
}