Algorithm/DS Problem #5: Rotate matrix by 90° anti-clockwise

Given a square matrix(n * n), you need to turn it 90 degrees in anti-clockwise direction without taking any extra space.

Input: 3 x 3 matrix
1 2 3
4 5 6
7 8 9

Output:
3 6 9
2 5 8
1 4 7