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.

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

求一个最大的矩形面积，之前想用dp思想来解决这道题，发现时间复杂度达到了n2，所以找了一下coder ganker的思想，使用一个栈有小到大存储遍历过的索引。

public class Solution {    public int largestRectangleArea(int[] height) {      if(height==null || height.length==0)          return 0;      int max = 0;      LinkedList<Integer> stack = new LinkedList<Integer>();      for(int i=0;i<height.length;i++)      {          while(!stack.isEmpty() && height[i]<=height[stack.peek()])          {              int index = stack.pop();              int curArea = stack.isEmpty()?i*height[index]:(i-stack.peek()-1)*height[index];              max = Math.max(max,curArea);          }          stack.push(i);      }      while(!stack.isEmpty())      {          int index = stack.pop();          int curArea = stack.isEmpty()?height.length*height[index]:(height.length-stack.peek()-1)*height[index];          max = Math.max(max,curArea);                  }      return max;  }  }