Queue Reversal.cpp

/*
Queue Reversal
==============

Given a Queue Q containing N elements. The task is to reverse the Queue. Your task is to complete the function rev(), that reverses the N elements of the queue.

Example 1:
Input:
6
4 3 1 10 2 6
Output: 
6 2 10 1 3 4
Explanation: 
After reversing the given
elements of the queue , the resultant
queue will be 6 2 10 1 3 4.

Example 2:
Input:
4
4 3 2 1 
Output: 
1 2 3 4
Explanation: 
After reversing the given
elements of the queue , the resultant
queue will be 1 2 3 4.

Your Task:
You only need to complete the function rev that takes a queue as parameter and returns the reversed queue. The printing is done automatically by the driver code.

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

Constraints:
1 ≤ N ≤ 105
1 ≤ elements of Queue ≤ 105
*/

queue<int> rev(queue<int> q)
{
  stack<int> s;
  while (!q.empty())
  {
    s.push(q.front());
    q.pop();
  }
  while (!s.empty())
  {
    q.push(s.top());
    s.pop();
  }
  return q;
}