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.
简单来说就是给你一个数组，在以下标位横坐标的x轴上画垂直于x轴的线，这个线的高度就是数组的值。用这些线来组成水槽，找到盛水最多的。
使用两个指针，指向开头和结尾，找到矮的那个，把指向它的指针往中间挪一个。
因为此时不管这个矮的和剩下的谁配，盛的水都不会比现在多，高度不会变，长度会变小。所以这个矮的就再也不用找了。
var maxArea = function(height) {
var max = 0;
var l = 0;
var r = height.length;
while (l<r) {
var now;
if (height[l]<height[r]) {
now = height[l] * (r-l);
l++;
} else {
now = height[r] * (r-l);
r--;
}
max = now > max ? now : max;
}
return max;
};
