Algorithm

Problem Name: Data Structures - Insert a Node at the Tail of a Linked List

Problem Link: https://www.hackerrank.com/challenges/print-the-elements-of-a-linked-list/problem?isFullScreen=true

In this HackerRank in Data Structures - Insert a Node at the Tail of a Linked List in List solutions

This challenge is part of a tutorial track by MyCodeSchool and is accompanied by a video lesson.

 

You are given the pointer to the head node of a linked list and an integer to add to the list. Create a new node with the given integer. Insert this node at the tail of the linked list and return the head node of the linked list formed after inserting this new node. The given head pointer may be null, meaning that the initial list is empty.

 

Function Description

 

Complete the insertNodeAtTail function in the editor below.

 

insertNodeAtTail has the following parameters:

 

  • SinglyLinkedListNode pointer head: a reference to the head of a list
  • int data: the data value for the node to insert

 

Returns

 

  • SinglyLinkedListNode pointer: reference to the head of the modified linked list

Input Format

The first line contains an integer n, the number of elements in the linked list.
The next n lines contain an integer each, the value that needs to be inserted at tail.

Constraints

  • 1 <= n <= 1000
  • 1 <= list[i] <= 1000

Sample Input

STDIN Function ----- -------- 5 size of linked list n = 5 141 linked list data values 141..474 302 164 530 474

Sample Output

141
302
164
530
474

Explanation

First the linked list is NULL. After inserting 141, the list is 141 -> NULL.
After inserting 302, the list is 141 -> 302 -> NULL.
After inserting 164, the list is 141 -> 302 -> 164 -> NULL.
After inserting 530, the list is 141 -> 302 -> 164 -> 530 -> NULL. After inserting 474, the list is 141 -> 302 -> 164 -> 530 -> 474 -> NULL, which is the final list.

 

 

 

Code Examples

#1 Code Example with C Programming

Code - C Programming


#include <assert.h>
#include <limits.h>
#include <math.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

char* readline();

typedef struct SinglyLinkedListNode SinglyLinkedListNode;
typedef struct SinglyLinkedList SinglyLinkedList;

struct SinglyLinkedListNode {
    int data;
    SinglyLinkedListNode* next;
};

struct SinglyLinkedList {
    SinglyLinkedListNode* head;
};

SinglyLinkedListNode* create_singly_linked_list_node(int node_data) {
    SinglyLinkedListNode* node = malloc(sizeof(SinglyLinkedListNode));

    node->data = node_data;
    node->next = NULL;

    return node;
}

void print_singly_linked_list(SinglyLinkedListNode* node, char* sep, FILE* fptr) {
    while (node) {
        fprintf(fptr, "%d", node->data);

        node = node->next;

        if (node) {
            fprintf(fptr, "%s", sep);
        }
    }
}

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

        free(temp);
    }
}

// Complete the insertNodeAtTail function below.

SinglyLinkedListNode* insertNodeAtTail(SinglyLinkedListNode* head, int data) {
    if (head == NULL) {
        return create_singly_linked_list_node(data);
    }
    
    SinglyLinkedListNode *node = head;
    while (node->next != NULL) {
        node = node->next;
    }
    node->next = create_singly_linked_list_node(data);
    return head;
}

int main()
{
    FILE* fptr = fopen(getenv("OUTPUT_PATH"), "w");

    SinglyLinkedList* llist = malloc(sizeof(SinglyLinkedList));
    llist->head = NULL;
  
    char* llist_count_endptr;
    char* llist_count_str = readline();
    int llist_count = strtol(llist_count_str, &llist_count_endptr, 10);

    if (llist_count_endptr == llist_count_str || *llist_count_endptr != '\0') { exit(EXIT_FAILURE); }

    for (int i = 0; i  <  llist_count; i++) {
        char* llist_item_endptr;
        char* llist_item_str = readline();
        int llist_item = strtol(llist_item_str, &llist_item_endptr, 10);

        if (llist_item_endptr == llist_item_str || *llist_item_endptr != '\0') { exit(EXIT_FAILURE); }

		SinglyLinkedListNode* llist_head = insertNodeAtTail(llist->head, llist_item);
        llist->head = llist_head;
    }



    char *sep = "\n";

    print_singly_linked_list(llist->head, sep, fptr);
    fprintf(fptr, "\n");

    free_singly_linked_list(llist->head);

    fclose(fptr);

    return 0;
}

char* readline() {
    size_t alloc_length = 1024;
    size_t data_length = 0;
    char* data = malloc(alloc_length);

    while (true) {
        char* cursor = data + data_length;
        char* line = fgets(cursor, alloc_length - data_length, stdin);

        if (!line) {
            break;
        }

        data_length += strlen(cursor);

        if (data_length  <  alloc_length - 1 || data[data_length - 1] == '\n') {
            break;
        }

        alloc_length <<= 1;

        data = realloc(data, alloc_length);

        if (!line) {
            break;
        }
    }

    if (data[data_length - 1] == '\n') {
        data[data_length - 1] = '\0';

        data = realloc(data, data_length);
    } else {
        data = realloc(data, data_length + 1);

        data[data_length] = '\0';
    }

    return data;
}
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#2 Code Example with C++ Programming

Code - C++ Programming


#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;

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

};

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);
    }
}


SinglyLinkedListNode* insertNodeAtTail(SinglyLinkedListNode* head, int data) {
    SinglyLinkedListNode *n = new SinglyLinkedListNode(data);
    if(head==NULL){
        return head=n;
    }
    else{
        SinglyLinkedListNode *rhead = head;
        while(head->next !=NULL){
            head=head->next;
        }
        head->next = n;
        return rhead;
    }
}

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');
    
        SinglyLinkedListNode* llist_head = insertNodeAtTail(llist->head, llist_item);
        llist->head = llist_head;
    }

    print_singly_linked_list(llist->head, "\n", fout);
    fout << "\n";

    free_singly_linked_list(llist->head);

    fout.close();

    return 0;
}
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#3 Code Example with Java Programming

Code - Java Programming


import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;

public class Solution {

    static class SinglyLinkedListNode {
        public int data;
        public SinglyLinkedListNode next;

        public SinglyLinkedListNode(int nodeData) {
            this.data = nodeData;
            this.next = null;
        }
    }

    static class SinglyLinkedList {
        public SinglyLinkedListNode head;

        public SinglyLinkedList() {
            this.head = null;
        }

      
    }

    public static void printSinglyLinkedList(SinglyLinkedListNode node, String sep, BufferedWriter bufferedWriter) throws IOException {
        while (node != null) {
            bufferedWriter.write(String.valueOf(node.data));

            node = node.next;

            if (node != null) {
                bufferedWriter.write(sep);
            }
        }
    }


    static SinglyLinkedListNode insertNodeAtTail(SinglyLinkedListNode head, int data) {
        SinglyLinkedListNode temp = head;
        if(temp == null){
            head = new SinglyLinkedListNode(data);
            return head;
        }
        while(temp.next != null){
            temp = temp.next;
        }
        temp.next = new SinglyLinkedListNode(data);
        return head;
    }

    private static final Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) throws IOException {
        BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

        SinglyLinkedList llist = new SinglyLinkedList();

        int llistCount = scanner.nextInt();
        scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");

        for (int i = 0; i < llistCount; i++) {
            int llistItem = scanner.nextInt();
            scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");
            
          SinglyLinkedListNode llist_head = insertNodeAtTail(llist.head, llistItem);

          llist.head = llist_head;
        }



        printSinglyLinkedList(llist.head, "\n", bufferedWriter);
        bufferedWriter.newLine();

        bufferedWriter.close();

        scanner.close(>;
    }
}
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#4 Code Example with Javascript Programming

Code - Javascript Programming


'use strict';

const fs = require('fs');

process.stdin.resume();
process.stdin.setEncoding('utf-8');

let inputString = '';
let currentLine = 0;

process.stdin.on('data', inputStdin => {
    inputString += inputStdin;
});

process.stdin.on('end', function() {
    inputString = inputString.replace(/\s*$/, '')
        .split('\n')
        .map(str => str.replace(/\s*$/, ''));

    main();
});

function readLine() {
    return inputString[currentLine++];
}

const SinglyLinkedListNode = class {
    constructor(nodeData) {
        this.data = nodeData;
        this.next = null;
    }
};

const SinglyLinkedList = class {
    constructor() {
        this.head = null;
    }

};

function printSinglyLinkedList(node, sep, ws) {
    while (node != null) {
        ws.write(String(node.data));

        node = node.next;

        if (node != null) {
            ws.write(sep);
        }
    }
}

function insertNodeAtTail(head, data) {
    if(!head){
        head = new SinglyLinkedListNode(data,null)
    }else {
        //find tail 
        let curr=head,next=null;
        while(curr.next){
            next = curr.next;
            curr = next;
        }
        curr.next = new SinglyLinkedListNode(data,null)
    }
    return head
}

function main() {
    const ws = fs.createWriteStream(process.env.OUTPUT_PATH);

    const llistCount = parseInt(readLine(), 10);

    let llist = new SinglyLinkedList();

    for (let i = 0; i < llistCount; i++) {
        const llistItem = parseInt(readLine(), 10);
    	const llist_head = insertNodeAtTail(llist.head, llistItem);
      	llist.head = llist_head;
    }

    printSinglyLinkedList(llist.head, '\n', ws);
    ws.write('\n');

    ws.end(>;
}
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#5 Code Example with Python Programming

Code - Python Programming


import math
import os
import random
import re
import sys

class SinglyLinkedListNode:
    def __init__(self, node_data):
        self.data = node_data
        self.next = None

class SinglyLinkedList:
    def __init__(self):
        self.head = None

def print_singly_linked_list(node, sep, fptr):
    while node:
        fptr.write(str(node.data))

        node = node.next

        if node:
            fptr.write(sep)


def insertNodeAtTail(head, data):
    cur = head
    if head == None:
        return SinglyLinkedListNode(data)
    while cur.next != None:
        cur = cur.next
    cur.next = SinglyLinkedListNode(data)
    return head

if __name__ == '__main__':
    fptr = open(os.environ['OUTPUT_PATH'], 'w')

    llist_count = int(input())

    llist = SinglyLinkedList()

    for i in range(llist_count):
        llist_item = int(input())
        llist_head = insertNodeAtTail(llist.head, llist_item)
        llist.head = llist_head

    print_singly_linked_list(llist.head, '\n', fptr)
    fptr.write('\n')

    fptr.close()
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Demonstration

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