LeetCode Q11: Container With Most Water

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.

• Mehtod1

Most naive way, two loops .

• Method2

• Method3

O(n) time method, use two pointers to scan the array once.
Suppose two points are s, e. In the beginning, s at the left end, e at the right end. The goal is to maximize the area. So, in this case, we always try to move the shortest bar between s and e to left(s) or to right(e) to look for next bigger area.