What 'left rotate by one' means

[1, 2, 3, 4, 5] becomes [2, 3, 4, 5, 1]. The first element wraps around to the end. Every other element moves one slot to the left.

The trick

You can't just do a[i] = a[i+1] for every i because the first element would be lost. So save it first:

first = a[0]
for i in 0..n-2:
    a[i] = a[i+1]
a[n-1] = first

O(n) time, O(1) extra memory.

Generalizing

To rotate by k positions you usually use the reversal trick: reverse a[0..k-1], reverse a[k..n-1], reverse the whole thing. That's a great follow-up to internalize once this one feels obvious.

Output

Print the rotated array space-separated on one line.