Question

I want to “wrap” around a list/vector in C++ like in Python. Basically I want to shift elements from the end of the list to beginning of the list. I don’t want to have to explicitly make a new list.

In Python I can write something like:

my_list = [1, 2, 3, 4, 5]
#[1, 2, 3, 4, 5]

q = collections.deque(my_list)
q.rotate(3)
#deque([3, 4, 5, 1, 2])

I looked at deque in the STL but I don’t see anything similar to rotate. Seems like there should be an easy way to do this with iterators, or something similar.

Answer 1

You are looking for std::rotate from the standard library, which offers an easy way to do this with iterators.

#include <algorithm>

std::vector<T> v /* = populate() */;
std::rotate(v.begin(), v.begin() + 3, v.end());

Any forward iterator can be used, so this works on most (sequence) containers.