Day 24 More Linked Lists Hackerrank Solution In C++ | 30 Days

Day 24 More Linked Lists Hackerrank Solution In C++. Under the 30 Days of Code, this is a Day 24 programming problem. Below is the hackerrank linked list problem statement.

Task: 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 a list).

A removeDuplicates function is declared in your editor, which takes a pointer to the head node of a linked list as a parameter. Complete removeDuplicates so that it deletes any duplicate nodes from the list and returns the head of the updated list.

Day 24 More Linked Lists Hackerrank Solution In C++

Note: The head pointer may be null, indicating that the list is empty. Be sure to reset your next pointer when performing deletions to avoid breaking the list.

Input Format

  1. You do not need to read any input from stdin. The following input is handled by the locked stub code and passed to the removeDuplicates function:
  2. The first line contains an integer, N, the number of nodes to be inserted.
  3. The N subsequent lines each contain an integer describing the data value of a node being inserted at the list's tail.


The data elements of the linked list argument will always be in non-decreasing order.

Output Format

Your removeDuplicates function should return the head of the updated linked list. The locked stub code in your editor will print the returned list to stdout.

Sample Input


Sample Output

1 2 3 4


N = 6, and our non-decreasing list is {1, 2, 2, 3, 3, 4}. The values 2 and 3 both occur twice in the list, so we remove the two duplicate nodes. We then return our updated (ascending) list, which is {1, 2, 3, 4}.

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Day 24 More Linked Lists Hackerrank Solution In C++

#include <cstddef>
#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>

using namespace std;
class Node {
  public: int data;
  Node * next;
  Node(int d) {
    data = d;
    next = NULL;
class Solution {
  public: Node * removeDuplicates(Node * head) {
    if (!head)
      return head;

    Node * node = head;
    while (node -> next) {
      if (node -> data == node -> next -> data)
        node -> next = node -> next -> next;
        node = node -> next;

    return head;
  Node * insert(Node * head, int data) {
    Node * p = new Node(data);
    if (head == NULL) {
      head = p;

    } else if (head -> next == NULL) {
      head -> next = p;

    } else {
      Node * start = head;
      while (start -> next != NULL) {
        start = start -> next;
      start -> next = p;

    return head;

  void display(Node * head) {
    Node * start = head;
    while (start) {
      cout << start -> data << " ";
      start = start -> next;

int main() {
  Node * head = NULL;
  Solution mylist;
  int T, data;
  cin >> T;
  while (T--> 0) {
    cin >> data;
    head = mylist.insert(head, data);
  head = mylist.removeDuplicates(head);



More Linked Lists Hackerrank Solution Output

More Linked Lists Hackerrank Solution Output

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