New update is available. Click here to update.

Queue Using Two Stacks

Posted: 14 Feb, 2021
Difficulty: Easy


Try Problem

You will be given ‘Q’ queries. You need to implement a queue using two stacks according to those queries. Each query will belong to one of these three types:

1 ‘X’: Enqueue element ‘X’  into the end of the nth queue. Returns true after the element is enqueued.

2: Dequeue the element at the front of the nth queue. Returns -1 if the queue is empty, otherwise, returns the dequeued element.
Enqueue means adding an element to the end of the queue, while Dequeue means removing the element from the front of the queue.
Input Format:
The first line of input contains an integer ‘Q’ denoting the number of queries. 

The next ‘Q’ lines specify the type of operation/query to be performed on the data structure.

Each query contains an integer ‘P’ denoting the type of query.

For query of type 1, the integer ‘P’ is equal to 1 and it is followed by one integer ‘X’ denoting the element on which operation is to be performed.

For query of type 2, the integer ‘P’ is equal to 2 which dequeues the element.
Output Format:
For each query, return the output returned after performing the corresponding operation on the data structure. 
You don’t need to print anything. It has already been taken care of. Just implement the given functions.
1 <= Q <= 10^5 
1 <= P <= 2
1 <= X <= 10^5

Time limit: 1 sec