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.

Note: You may not slant the container.

public int maxArea(int[] height) {
        if (height == null || height.length < 2) {
            return 0;
        }
        int ans = 0;
        int l = 0, r = height.length - 1;
        while (l < r) {
            ans = Math.max(ans, Math.min(height[l], height[r]) * (r - l));
            if (height[l] < height[r]) {
                l++;
            } else {
                r--;
            }
        }
        return ans;
    }