Fastest algorithm for circle shift N sized array for M position

Question

What is the fastest algorithm for circle shifting array for M positions?
For example, [3 4 5 2 3 1 4] shift M = 2 positions should be [1 4 3 4 5 2 3

Answer 1

It's just a matter of representation. Keep the current index as an integer variable and when traversing the array use modulo operator to know when to wrap around. Shifting is then only changing the value of the current index, wrapping it around the size of the array. This is of course O(1).

For example:

int index = 0;
Array a = new Array[SIZE];

get_next_element() {
    index = (index + 1) % SIZE; 
    return a[index];
}

shift(int how_many) {
    index = (index+how_many) % SIZE;
}