Implement Queue using array

Problem Statement - link #

Implement a Queue using an Array. Queries in the Queue are of the following type:

1. 1 x (a query of this type means pushing ‘x’ into the queue)
2. 2 (a query of this type means to pop element from queue and print the poped element)

Your Task: You are required to complete the two methods push() which take one argument an integer ‘x’ to be pushed into the queue and pop() which returns a integer poped out from othe queue. If the queue is empty, it should return -1 on a pop operation.

Expected Time Complexity: O(1)
Expected Auxiliary Space: O(1)

Examples #

Example 1:

Input:
Q = 5
Queries = 1 2 1 3 2 1 4 2
Output: 2 3
Explanation:
In the first test case for query 
1 2 the queue will be {2}
1 3 the queue will be {2 3}
2   poped element will be 2 the 
    queue will be {3}
1 4 the queue will be {3 4}
2   poped element will be 3 

Example 2:

Input:
Q = 4
Queries = 1 3 2 2 1 4   
Output: 3 -1
Explanation:
In the second testcase for query 
1 3 the queue will be {3}
2   poped element will be 3 the
    queue will be empty
2   there is no element in the
    queue and hence -1
1 4 the queue will be {4}. 

Constraints #

• 1 <= Q <= 10^5
• 1 <= x <= 10^5

Solutions #

//Function to push an element x in a queue.
void MyQueue :: push(int x)
{
    // Your Code
    arr[rear++] = x;
}

//Function to pop an element from queue and return that element.
int MyQueue :: pop()
{
    // Your Code   
    if(rear!=front) return arr[front++];
    return -1;
}