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.
谷歌翻译拉过来：
给定n个非负整数a1，a2，...，an，其中每个代表坐标（i，ai）处的一个点。 绘制n条垂直线，使得线i的两个端点处于（i，ai）和（i，0）处。 找到两条线，它们与x轴一起形成一个容器，使得容器包含最多的水。
注意：不倾斜容器，n至少为2。
题意：