Container With Most Water

leetcode 11

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：题目要求是x轴上在1,，2...n点上有许多垂直的线段，长度依次是a1，a2...an.找出两条线段，使他们和x轴围成的面积最大。
弄两个指针l和r，从头尾开始，如果height[l]<height[r],在往中间移动的过程中x轴即底是变小的，所以只能让低的height变化面积才会有变化，变高的话就更新面积，不变的话就不更新面积，更新后将l++，反之r--。

var maxArea = function(height) {
    var l=0;
    var r=height.length-1;
    var res=Math.min(height[l],height[r])*(r-l);
    while(l<r){
        if(height[l]<height[r]){
            res=Math.max(res,(r-l)*height[l])
            l++; 
        }else{
            res=Math.max(res,(r-l)*height[r]);
             r--;
        }
    }
    return res;
};