Cyclic Rotation In Python

Task: An array A consisting of N integers is given. Rotation of the array means that each element is shifted right by one index, and the last element of the array is moved to the

Solution 1:

The problem is that you are simply assigning a new variable name to your new list when you do old = new. So whatever changes you now do to new will also be reflected in old because you simply created a new pointer to the same memory location of the new list. You should create a copy of the list so that you do not modify the original list. One way to do so is old = new.copy()

def solution(A , K):
     old = A
     new = [0]*len(A)
     for i in range(K):
         new[0]=old[-1]
         new[1:] = old[:-1]
         old = new.copy() # This was the problematic line
     return new

solution([1,2,3,4,5], 2)
# [4, 5, 1, 2, 3]

solution([1,2,3,4,5], 3)
# [3, 4, 5, 1, 2]