11. 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.

两边设一个指针，然后计算area，如果height[i] <= height[j]，那么i++，因为在这里height[i]是瓶颈，j往里移只会减少面积，不会再增加area。
这是一个贪心的策略，每次取两边围栏最矮的一个推进，希望获取更多的水。
class Solution {
public:
int maxArea(vector<int>& height) {
int res = 0;
int i = 0,j=height.size()-1;
while(i<j){
res = max(res, min(height[i],height[j])*(j-i));
height[i] > height[j]? j--:i++;
}
return res;
}
};