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

Answer 1

I came across the following implementation:

For square matrices:

for n = 0 to N - 2
    for m = n + 1 to N - 1
        swap A(n,m) with A(m,n)

For rectangular matrices:

for each length>1 cycle C of the permutation
    pick a starting address s in C
    let D = data at s
    let x = predecessor of s in the cycle
    while x ≠ s
        move data from x to successor of x
        let x = predecessor of x
    move data from D to successor of s

For more info, one can refer here: http://en.wikipedia.org/wiki/In-place_matrix_transposition