1. Given matrix of dimension M x N, rotate the matrix by 90 degree clockwise without using any extra space.

eg:
input:
1 2 3
4 5 6
7 8 9
10 11 12

output:

10  7  4  1
11  8  5  2
12  9  6  3

2. Vertical order traversal of a binary tree.

Question 1 can be easily solved if dimensions of the matrix is same(i.e. NxN) but was not able to find the solution for MxN dimensions. Any suggestions will be helpful.