Tag Archives: linked list

Hackerrank “30 Days of Code” Çözümleri – Day 15: Linked List

Hackerrank’in 30 Days of Code içerisinde bulunan “Day 15: Linked List” sorusunun açıklaması ve çözümü. Bu soruda linked list veri yapısına ve içerisindeki node’larda iterasyon yapılmasına göz atıyoruz.

► Hackerrank 30 Days of Code Çözümleri – Day 15: Linked List: https://www.hackerrank.com/challenges/30-linked-list/problem

► Problem açıklaması:


Today we will work with a Linked List. Check out the Tutorial tab for learning materials and an instructional video.

A Node class is provided for you in the editor. A Node object has an integer data field, data, and a Node instance pointer, next, pointing to another node (i.e.: the next node in the list).

A Node insert function is also declared in your editor. It has two parameters: a pointer, head, pointing to the first node of a linked list, and an integer, data, that must be added to the end of the list as a new Node object.


Complete the insert function in your editor so that it creates a new Node (pass data as the Node constructor argument) and inserts it at the tail of the linked list referenced by the head parameter. Once the new node is added, return the reference to the head node.

Note: The head argument is null for an empty list.

Input Format

The first line contains T, the number of elements to insert.

Each of the next T lines contains an integer to insert at the end of the list.

Output Format

Return a reference to the head node of the linked list.

Sample Input

STDIN Function

—– ——–

4 T = 4

2 first data = 2



1 fourth data = 1

Sample Output

2 3 4 1


T = 4, so your method will insert 4 nodes into an initially empty list. First the code returns a new node that contains the data value 2 as the head of the list. Then create and insert nodes 3, 4, and a at the tail of the list.

HackerRank Çözümleri – Cycle Detection

HackerRank içerisinde bulunan “Cycle Detection” sorusunun açıklaması ve çözümü. Bu soruda size verilen bir linked list içerisinde döngüsel bir yapı olup olmadığını bulmanız isteniyor.

► HackerRank – Cycle Detection: https://www.hackerrank.com/challenges/detect-whether-a-linked-list-contains-a-cycle/problem

► Problem açıklaması:

A linked list is said to contain a cycle if any node is visited more than once while traversing the list. Given a pointer to the head of a linked list, determine if it contains a cycle. If it does, return 1. Otherwise, return 0.


head refers to the list of nodes 1 — 2 — 3 — NULL

The numbers shown are the node numbers, not their data values. There is no cycle in this list so return 0.

head refers to the list of nodes 1 — 2 — 3 — 1 — NULL

There is a cycle where node 3 points back to node 1, so return 1.

Function Description

Complete the has_cycle function in the editor below.

It has the following parameter:

SinglyLinkedListNode pointer head: a reference to the head of the list


int:1 if there is a cycle or 0 if there is not

Note: If the list is empty, head will be null.

Input Format

The code stub reads from stdin and passes the appropriate argument to your function. The custom test cases format will not be described for this question due to its complexity. Expand the section for the main function and review the code if you would like to figure out how to create a custom case.