How to rotate a matrix 90 degrees without using any extra space? [duplicate]

Question

Possible Duplicate:
Algorithm to rotate an image 90 degrees in place? (No extra memory)

By saying 90 degrees i mean to say if:

A = {1,2,3,      4,5,6,      7,8,9} 

then after 90 degree rotation A becomes:

A = {7,4,1,      8,5,2,      9,6,3} 

Answer 1

Transpose and interchange rows or columns (depends whether you want to rotate left or right).

e. g.

1) original matrix  1 2 3 4 5 6 7 8 9  2) transpose  1 4 7 2 5 8 3 6 9  3-a) change rows to rotate left  3 6 9 2 5 8 1 4 7  3-b) or change columns to rotate right  7 4 1 8 5 2 9 6 3 

All these operations can be done without allocating memory.