[Lintcode]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.

Example

Given 

[1,3,2]

, the max
area of the container is 

2

.

使用O（N×N）算法会超时。另外一种O（N）算法的思想是，每次放弃ai，aj中最小的，因为假如ai较小，那么以ai为左边界遍历的所有结果不会超过当前的容量。所以放弃ai， i++。如此一来避免了不必要的计算。

public class Solution {
/**
* @param heights: an array of integers
* @return: an integer
*/
public int maxArea(int[] heights) {
int left = 0, right = heights.length - 1;
int res = 0;
while(left < right) {
int tmp = heights[left] > heights[right] ? heights[right] : heights[left];
res = Math.max(res, tmp * (right - left));
if(heights[left] > heights[right]) right --;
else left ++;
}
return res;
}
}