题目
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.
Example 1:
Input: [1,8,6,2,5,4,8,3,7]
Output: 49
题目大意
给出一个非负整数数组 a1,a2,a3,…… an,每个整数标识一个竖立在坐标轴 x 位置的一堵高度为 ai 的墙,选择两堵墙,和 x 轴构成的容器可以容纳最多的水。
解题思路
这一题也是对撞指针的思路。首尾分别 2 个指针,每次移动以后都分别判断长宽的乘积是否最大。