Reverse Queue

 

You have been given a queue that can store integers as the data. You are required to write a function that reverses the populated queue itself without using any other data structures.

Example:

Input Format:

The first list of input contains an integer 't' denoting the number of test cases/queries to be run.
Then the test cases follow.

The first line input for each test case/query contains an integer N, denoting the total number of elements in the queue.

The second line of input contains N integers separated by a single space, representing the order in which the elements are enqueued into the queue.

Output Format:

For each test case/query, the only line of output prints the order in which the queue elements are dequeued, all of them separated by a single space.

Output for every test case/query will be printed on a new line. 

Note:

You are not required to print the expected output explicitly, it has already been taken care of. Just make the changes in the input queue itself.

Constraints:

1 <= t <= 100
1 <= N <= 10^4
-2^31 <= data <= 2^31 - 1

Time Limit: 1sec 

Sample Input 1:

1
6
1 2 3 4 5 10

Note:

Here, 1 is at the front and 10 is at the rear of the queue.

Sample Output 1:

10 5 4 3 2 1

Sample Input 2:

2
5
2 8 15 1 10
3
10 20 30

Sample Output 2:

10 1 15 8 2 
30 20 10 

#include <iostream>
using namespace std;

#include "solution.h"

int main() {
    int t;
    cin >> t;

    while (t--) {
        queue<int> q;
        int size;
        cin >> size;

        for (int i = 0, val; i < size; i++) {
            cin >> val;
            q.push(val);
        }

        reverseQueue(q);
        while (!q.empty()) {
            cout << q.front() << " ";
            q.pop();
        }

        cout << "\n";
    }
}




#include<bits/stdc++.h>
void reverseQueue(queue<int> &input) {
	// Write your code here
    //if(input.empty())return;
    stack<int>st;
    while(!input.empty()){
        st.push(input.front());
        input.pop();
    }
    while(!st.empty()){
        input.push(st.top());
        st.pop();
    }
}