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

Answer 1

You need one temp variable, then it is just to jump elements around.

temp = A[0];
A[0] = A[6];
A[6] = A[8];
A[8] = A[2];
A[2] = temp;
temp = A[1];
A[1] = A[3];
A[3] = A[7];
A[7] = A[5];
A[5] = temp;