left rotate array in place C++

Question

THis is what I want to do: array A[] = {1,2,3,4,5} left rotate by 2: A:{3,4,5,1,2}

do we have a simple and good solution for doing this in place? I want the array A itself to be updated with this left rotated value - with no additional space.

I tried various approaches but the logic seems different for various test cases and had a hard time finding one algorithm that fits for this seemingly simple task.

NOTE: I know this can be easily done by just creating a new array with the left rotated values. I am trying to do this in the input array itself.

Pls suggest. Simple pseudo code should do.

Answer 1

std::rotate() will do exactly what you need:

auto b = std::begin(A);
std::rotate( b, b + 2, std::end(A) );