HackerRank•May 30, 2025

Delete a Node

Hazrat Ali

HackerRank

Delete the node at a given position in a linked list and return a reference to the head node. The head is at position 0. The list may be empty after you delete the node. In that case, return a null value.

Example

After removing the node at position , .

Function Description

Complete the deleteNode function in the editor below.

deleteNode has the following parameters:
- SinglyLinkedListNode pointer llist: a reference to the head node in the list
- int position: the position of the node to remove

Returns
- SinglyLinkedListNode pointer: a reference to the head of the modified list

Input Format

The first line of input contains an integer , the number of elements in the linked list.
Each of the next  lines contains an integer, the node data values in order.
The last line contains an integer, , the position of the node to delete.

Constraints

  • , where  is the  element of the linked list.

Sample Input

8
20
6
2
19
7
4
15
9
3

Sample Output

20 6 2 7 4 15 9



Solution
#include <bits/stdc++.h>

using namespace std;

class SinglyLinkedListNode {
    public:
        int data;
        SinglyLinkedListNode *next;

        SinglyLinkedListNode(int node_data) {
            this->data = node_data;
            this->next = nullptr;
        }
};

class SinglyLinkedList {
    public:
        SinglyLinkedListNode *head;
        SinglyLinkedListNode *tail;

        SinglyLinkedList() {
            this->head = nullptr;
            this->tail = nullptr;
        }

        void insert_node(int node_data) {
            SinglyLinkedListNode* node = new SinglyLinkedListNode(node_data);

            if (!this->head) {
                this->head = node;
            } else {
                this->tail->next = node;
            }

            this->tail = node;
        }
};

void print_singly_linked_list(SinglyLinkedListNode* node, string sep, ofstream& fout) {
    while (node) {
        fout << node->data;

        node = node->next;

        if (node) {
            fout << sep;
        }
    }
}

void free_singly_linked_list(SinglyLinkedListNode* node) {
    while (node) {
        SinglyLinkedListNode* temp = node;
        node = node->next;

        free(temp);
    }
}

/*
 * Complete the 'deleteNode' function below.
 *
 * The function is expected to return an INTEGER_SINGLY_LINKED_LIST.
 * The function accepts following parameters:
 *  1. INTEGER_SINGLY_LINKED_LIST llist
 *  2. INTEGER position
 */

/*
 * For your reference:
 *
 * SinglyLinkedListNode {
 *     int data;
 *     SinglyLinkedListNode* next;
 * };
 *
 */

SinglyLinkedListNode* deleteNode(SinglyLinkedListNode* head, int position) {

    if (position == 0) {
        SinglyLinkedListNode* next = head->next;
        delete head;
        return next;
    }

    SinglyLinkedListNode* temp = head;
    SinglyLinkedListNode* prev;
    int pos = 0;
    while (temp != nullptr) {
        if (pos == position) break;
        prev = temp;
        temp = temp->next;
        pos++;
    }

    prev->next = temp->next;

    delete temp;
    return head;
}
int main()
{
    ofstream fout(getenv("OUTPUT_PATH"));

    SinglyLinkedList* llist = new SinglyLinkedList();

    int llist_count;
    cin >> llist_count;
    cin.ignore(numeric_limits<streamsize>::max(), '\n');

    for (int i = 0; i < llist_count; i++) {
        int llist_item;
        cin >> llist_item;
        cin.ignore(numeric_limits<streamsize>::max(), '\n');

        llist->insert_node(llist_item);
    }

    int position;
    cin >> position;
    cin.ignore(numeric_limits<streamsize>::max(), '\n');

    SinglyLinkedListNode* llist1 = deleteNode(llist->head, position);

    print_singly_linked_list(llist1, " ", fout);
    fout << "\n";

    free_singly_linked_list(llist1);

    fout.close();

    return 0;
}







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