Graduate Software Intern

Implement a queue data structure which follows FIFO(First In First Out) property, using only the instances of the stack data structure.

Note:

1. To implement means you need to complete some predefined functions, which are supported by a normal queue such that it can efficiently handle the given input queries which are defined below.


2. The implemented queue must support the following operations of a normal queue: 

a. enQueue(data) : This function should take one argument of type integer and place the integer to the back of the queue.

b. deQueue(): This function should remove an integer from the front of the queue and also return that integer. If the queue is empty, it should return -1.

c. peek(): This function returns the element present in the front of the queue. If the queue is empty, it should return -1.

d. isEmpty(): This function should return true if the queue is empty and false otherwise.


3. You will be given q queries of 4 types:

a. 1 val - For this type of query, you need to insert the integer val to the back of the queue.

b. 2 - For this type of query, you need to remove the element from the front of the queue, and also return it.

c. 3 - For this type of query, you need to return the element present at the front of the queue(No need to remove it from the queue).

d. 4 - For this type of query, you need to return true if the queue is empty and false otherwise.


4. For every query of type:

a. 1, you do not need to return anything.

b. 2, return the integer being deQueued from the queue.

c. 3, return the integer present in the front of the queue.

d. 4, return “true” if the queue is empty, “false” otherwise.

Example

Operations: 
1 5
1 10
2
3
4

Enqueue operation 1 5: We insert 5 at the back of the queue.
Queue: [5]

Enqueue operation 1 10: We insert 10 at the back of the queue.
Queue: [5, 10]

Dequeue operation 2: We remove the element from the front of the queue, which is 5, and print it.
Output: 5
Queue: [10]

Peek operation 3: We return the element present at the front of the queue, which is 10, without removing it.
Output: 10
Queue: [10]

IsEmpty operation 4: We check if the queue is empty.
Output: False
Queue: [10]

You are given two Singly Linked Lists of integers, which may have an intersection point.

Your task is to return the first intersection node. If there is no intersection, return NULL.

Example:-

The Linked Lists, where a1, a2, c1, c2, c3 is the first linked list and b1, b2, b3, c1, c2, c3 is the second linked list, merging at node c1.

You are given a string 'S'. Your task is to check whether the string is palindrome or not. For checking palindrome, consider alphabets and numbers only and ignore the symbols and whitespaces.

Note :

String 'S' is NOT case sensitive.

Example :

Let S = “c1 O$d@eeD o1c”.
If we ignore the special characters, whitespaces and convert all uppercase letters to lowercase, we get S = “c1odeedo1c”, which is a palindrome. Hence, the given string is also a palindrome.

You are given an array of integers 'ARR' containing N elements. Each integer is in the range [1, N-1], with exactly one element repeated in the array.

Your task is to find the duplicate element. The duplicate element may be repeated more than twice in the error, but there will be exactly one element that is repeated in the array.

Note :

All the integers in the array appear only once except for precisely one integer which appears two or more times.