rotate_with_reflections_en.py

def rotate_with_reflections(arr,k): #inputs are array and number of steps to move k
    n = len(arr)
    for i in range(n//2): #make the first reflection - line from the first element of the array
        buf = arr[i] #additional memory O(1)
        arr[i] = arr[n-1-i]
        arr[n-1-i] = buf
    for i in range(k//2): #second reflection is made by parts to ease up code:
        buf = arr[i] #additional memory O(1)
        arr[i] = arr[k-1-i]
        arr[k-1-i] = buf
    for i in range((n-k)//2): 
        buf = arr[k+i] #additional memory O(1)
        arr[k+i] = arr[n-1-i]
        arr[n-1-i] = buf
    #total additional memory is O(1)
    #time complexity is O(n) since every element is traversed no more than two times
    return arr

print(rotate_with_reflections(list(range(10)),3))
#Output: [7, 8, 9, 0, 1, 2, 3, 4, 5, 6]