leetcode 11. Container With Most Water (two pointer)

Given n non-negative integers a1, a2, ..., an, where each represents a point at coordinate (i, ai). n vertical lines are drawn such that the two endpoints of line i is at (i, ai) and (i, 0). Find two lines, which together with x-axis forms a container, such that the container contains the most water.

Note: You may not slant the container and n is at least 2.

题意：n条竖直的线段 (i,0)->(i,a[i]),从中选2条，和x轴共同组成一个开口的容器，问容器的最大面积。

思路：一开始想错了，以为是最大连续矩形面积...还在想leetcode竟然考单调栈？？？

然而实际上只取两个线段，中间的线段有没有，长度，都是无所谓的。

因此two pointer就好了。。。

/* ***********************************************
Author :111qqz
Created Time :2017年04月13日 星期四 18时06分42秒
File Name :11.cpp
 ************************************************ */
class Solution {

    public:

	int maxArea(vector<int>& height) {
	    int res = 0 ;
	    int n = height.size();
	    int head = 0 ;
	    int tail = n-1;
	    while (head<tail)
	    {
		int h = min(height[head],height[tail]);
		res = max(res,(tail-head)*h);
		while (head<tail&&height[head]<=h) head++;
		while (head<tail&&height[tail]<=h) tail--;
	    }
	    return res;


	}

};