Spiral Matrix

[MD571]

Feature description

Given a 2D array, print it in spiral form.

Examples:

Input: {{1, 2, 3, 4},
{5, 6, 7, 8},
{9, 10, 11, 12},
{13, 14, 15, 16 }}
Output: 1 2 3 4 8 12 16 15 14 13 9 5 6 7 11 10
Explanation: The output is matrix in spiral format