11. Container With Most Water Medium

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.

思路： 1.双层循环逐个算出每个容器的装水量，比较选出最大的一个。复杂度为O(n ＾２)，超时。

　２.先算出最外层的容器装水量，若不是最大的，那么最大的容器必定没它宽，而最大的容器高度一定比最外层的高，所以我们每次只需将短边向内移动，比较出最大的容器，复杂度为Ｏ(n)。

注意：短板效应。

class Solution {public:    int maxArea(vector<int>& height) {        int result = 0;        for (int i = 0, j = height.size() - 1; i < j;) {                int high = min(height[i], height[j]);                if (high * (j - i) > result)                result = high * (j - i);                if (high == height[i]) {                    i++;                } else {                    j--;                }            }        return result;    }};