Reverse First K elements of Queue.cpp

/*
Reverse First K elements of Queue
=================================

Given an integer K and a queue of integers, we need to reverse the order of the first K elements of the queue, leaving the other elements in the same relative order.

Only following standard operations are allowed on queue.

enqueue(x) : Add an item x to rear of queue
dequeue() : Remove an item from front of queue
size() : Returns number of elements in queue.
front() : Finds front item.

Example 1:
Input:
5 3
1 2 3 4 5
Output: 
3 2 1 4 5
Explanation: 
After reversing the given
input from the 3rd position the resultant
output will be 3 2 1 4 5.

Example 2:
Input:
4 4
4 3 2 1
Output: 
1 2 3 4
Explanation: 
After reversing the given
input from the 4th position the resultant
output will be 1 2 3 4.
Your Task:
Complete the provided function modifyQueue that takes queue and k as parameters and returns a modified queue. The printing is done automatically by the driver code.

Expected TIme Complexity : O(n)
Expected Auxilliary Space : O(n)

Constraints:
1 <= N <= 1000
1 <= K <= N

Note:The Input/Ouput format and Example given are used for system's internal purpose, and should be used by a user for Expected Output only. As it is a function problem, hence a user should not read any input from stdin/console. The task is to complete the function specified, and not to write the full code.
*/

queue<int> modifyQueue(queue<int> q, int k)
{
  stack<int> st;
  queue<int> qt;

  for (int i = 0; i < k; ++i)
  {
    st.push(q.front());
    q.pop();
  }

  while (q.size())
  {
    qt.push(q.front());
    q.pop();
  }

  while (st.size())
  {
    q.push(st.top());
    st.pop();
  }

  while (qt.size())
  {
    q.push(qt.front());
    qt.pop();
  }

  return q;
}