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Queue Using Two Stacks

Posted: 14 Feb, 2021
Difficulty: Easy

PROBLEM STATEMENT

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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.
Note:
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. 
Note:
You don’t need to print anything. It has already been taken care of. Just implement the given functions.
Constraints:
1 <= Q <= 10^5 
1 <= P <= 2
1 <= X <= 10^5

Time limit: 1 sec