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 height = [2,1,5,6,2,3],
return 10.

 

public class Solution {
    public int largestRectangleArea(int[] height) {
    	Stack<Integer> stack = new Stack<Integer>();
    	int i = 0;
    	int maxArea = 0;
    	int[] tmp = Arrays.copyOf(height, height.length+1);
    	while (i < tmp.length) {
    		if (stack.isEmpty() || tmp[stack.peek()] <= tmp[i]) {
    			stack.push(i++);
    		} else {
    			int t = stack.pop();
    			maxArea = Math.max(maxArea, tmp[t]*(stack.isEmpty() ? i: (i-stack.peek()-1)));
    		}
    	}
    	return maxArea;
    }
}