Linked List

You are given 2 sorted linked lists with a head pointer. Find a way to merge these 2 lists and return a single sorted list. Try to solve the problem without using any extra space. Example 1:List 1: 1 -> 2 -> 4List 2: 1 -> 3 -> 4Output: 1 -> 1 -> 2 -> 3 -> 4 -> 4 Problem statement To read about Linked Lists, refer to the post “What is a Linked List“? For our current problem statement, we are given two list heads or we refer…

Question: Given a linked list, return the node where the cycle begins. If there is no cycle, return null. Output: 0 The easier method to find the cycle has been discussed in this post. This method is based upon the idea of a circular race track. If there is a slow runner and a fast runner, eventually the fast runner will catch up the slow runner from behind. A similar analogy can be applied to a tortoise and a hare and hence the method is also called Tortoise and Hare…

Question: Given a linked list, return the node where the cycle begins. If there is no cycle, return null. Output: 0 We are given a linked list which may or may not have a loop. A loop in a linked list means that if we keep doing a next, we will never reach null. Thus, we can be clear of a fact that if we reach null, then the list does not have a loop. So how do we detect if there is a loop in the linked list. One…

Question: Given a sorted Linked List. Write a program to remove all the duplicates. Input: 4 -> 8 -> 8 -> 8 -> 15 -> 16 -> 23 -> 23 -> 42. Output: 4 -> 8 -> 15 -> 16 -> 23 -> 42 In a sorted Linked List, all the node that are duplicate will be together. To remove duplicates we need to traverse the linked list and if two adjacent nodes have same value, remove one of them. If adjacent node have different value then move forward. Time…

Question: Write a program to check if 2 linked lists are identical? Method 1(Iterative):- To Determine if both Linked lists are identical, we need to traverse both lists simultaneously, and while traversing we need to compare data of each node. Implementation Method2( Recursive):- It may seem that both recursive and iterative implementation are the same but the iterative version is recommended since it offers better control and the recursive implementation maintains a stack of all the callbacks.

An implementation of stack is similar to that of a Linked List. We will try to discuss the basic operations in a stack discussed in this post. MAIN OPERATIONS ON A STACK:- push( int ) :- Inserts a data into the stack pop :- Returns the topmost data from the stack AUXILIARY OPERATIONS ON A STACK int Top( ) :- returns the topmost element on the stack int Size( ) :- returns the total size of the stack int isStackEmpty( ) :- returns true if the stack is empty The…

Question: You are given the head pointer to 2 single Linked Lists, and both of the lists converge at a certain point and then advance forward. We need to find the address of the node, at which both of the Linked Lists meet. Input: 4 -> 8 -> 15 ->                               42 -> 99     16 -> 23 -> Output: 42 Suppose there are two single Linked Lists both of which intersect at some point and become a single Linked list. The head or start pointer of both the lists…

Copying an entire Linked List, means allocating new memory and copying all the data to the new location. This requires traversing each node and copying its data to a new location, keeping the original data intact.

Question: Write a program to check if the given Linked List is a palindrome or not? Input: 1.> 4, 8, 15, 16, 23, 42 2.> 4, 8, 15, 16, 15, 8, 4 Output: 1.> IS NOT A PALINDROME 2.> IS A PALINDROME What is a Palindrome? According to Wikipedia, A palindrome is a word, phrase, number, or other sequence of symbols or elements, whose meaning may be interpreted the same way in either forward or reverse direction. Thus, numbers like 121, 1331, 98711789 are palindromes. Similarly, Linked Lists can be…

Question: Given a Linked List, we need to find the middle of the list and print the number. Input: 4, 8, 15, 16, 23, 42, 99 Output: 16 This is a very basic question and is a part of a bigger problem. However, there are several approaches to solve the above problem. BRUTE-FORCE APPROACH In this approach, we count the number of nodes in the list for each of the node and see whether it is the middle. Time Complexity: O(n2) Space Complexity: O(1) MORE SIMPLIFIED APPROACH In this approach,…