How Can I Efficiently Extract a Subvector from a C Vector?

Extracting a Subvector from a Vector Efficiently

Suppose you want to extract a portion of a vector, creating a new vector with elements X through Y. In C with the standard library vector, the most straightforward approach is to use iterators:

vector<T>::const_iterator first = myVec.begin() + X;
vector<T>::const_iterator last = myVec.begin() + Y + 1;
vector<T> newVec(first, last);

This operation has an O(N) time complexity, where N is the size of the original vector. However, it's important to note that there isn't a significantly more efficient way to achieve this using a vector.

Alternative STL Datatype

If you need to extract subvectors frequently, consider using an alternative STL container that supports more efficient subvector extraction. One option is the deque, which allows for efficient insertion and deletion of elements at both ends:

deque<T> myDeque;
deque<T> subDeque(myDeque.begin() + X, myDeque.begin() + Y + 1);

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