题目描述：

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.

The above vertical lines are represented by array [1,8,6,2,5,4,8,3,7]. In this case, the max area of water (blue section) the container can contain is 49.

思路：

left = 0, right = n-1

1. a[left] < a[right], left++
2. a[left] > a[right], right–
3. a[left] = a[right], left++, right–

Runtime：20ms Memory：10.2MB