[Leetcode] 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.

一开始感觉跟Trapping Rain Water这题很像，就按着那题的想法写了，可是总是WA，后来好好一想发现不对，其实这题比那题还简单一点，想法跟数组中求和为给定值的两数一样。所谓容积其实就是面积，我们都知道长方形的面积=长*宽，不妨我们就从长最长的长方形找起，即令left = 0， right = height.size() - 1，但是在找下一个长方形时，长肯定会变短，要弥补这一段损失就必须加宽宽度，所以一下个就换掉两条宽中较小的那一个。代码也很简单：

 1 class Solution {

 2 public:

 3     int maxArea(vector<int> &height) {

 4         int maxArea = 0, area;

 5         int left = 0, right = height.size() - 1;

 6         while (left < right) {

 7             area = (right - left) * min(height[left], height[right]);

 8             maxArea = (maxArea > area) ? maxArea : area;

 9             if (height[left] < height[right])

10                 ++left;

11             else

12                 --right;

13         }

14         return maxArea;

15     }

16 };