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.

The above vertical lines are represented by array [1,8,6,2,5,4,8,3,7].
In this case, the max area of water (blue section)
the container can contain is 49.     

Example:
Input: [1,8,6,2,5,4,8,3,7]
Output: 49

    y
    ^
    |
    |     a2
    |     |  a3          an
    |  a1 |  |     a5    |
    |  |  |  |  a4 |     |
    |  |  |  |  |  | ..  |
    --------------------------->
   0   1  2  3  4  5 ..  n     x

public static int max(int[] A) {  

    int S = 0, i = 0, j = A.length -1;
    while (i < j) {
        S = Math.max(S, (j - i) * Math.min(A[i], A[j]));
        if (A[i] < A[j]) i++; else j--;
    }
    return S;
}