# HackerRank Insert a node at the head of a linked list problem solution

In this HackerRank Insert a node at the head of a linked list problem we need to develop a program in which if we have given a head node pointer of a linked list and the value that we need to add to the list. so we need to create a new node and assign that value to the node and then we need to insert that node at the head of the linked list and then return the reference of a new head node of that linked list.

## Problem solution in Python programming.

```#!/bin/python3

import math
import os
import random
import re
import sys

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

def __init__(self):
self.tail = None

while node:
fptr.write(str(node.data))

node = node.next

if node:
fptr.write(sep)

if llist:
node.next = llist
return node

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

llist_count = int(input())

for _ in range(llist_count):
llist_item = int(input())

fptr.write('\n')

fptr.close()
```

## Problem solution in 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 {

public int data;

this.data = nodeData;
this.next = null;
}
}

this.tail = 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);
}
}
}

if(llist == null){
return llist;
}
temp.next = llist;
llist = temp;
return llist;
}

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")));

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])?");

}

bufferedWriter.newLine();

bufferedWriter.close();

scanner.close();
}
}```

### Problem solution in C++ programming.

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

using namespace std;

public:
int data;

this->data = node_data;
this->next = nullptr;
}
};

public:

this->tail = nullptr;
}

};

while (node) {
fout << node->data;

node = node->next;

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

while (node) {
node = node->next;

free(temp);
}
}

newN->next = llist;
return newN;

}

int main()
{
ofstream fout(getenv("OUTPUT_PATH"));

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');

}

fout << "\n";

fout.close();

return 0;
}```

### Problem solution in 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>

int data;
};

};

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

return node;
}

while (node) {
fprintf(fptr, "%d", node->data);

node = node->next;

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

while (node) {
node = node->next;

free(temp);
}
}

// Complete the insertNodeAtHead function below.

/*
*
*     int data;
* };
*
*/

newnode->next = llist;
return newnode;
}

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

llist->tail = NULL;

char* llist_count_endptr;
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;
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); }

}

char *sep = "\n";

fprintf(fptr, "\n");

fclose(fptr);

return 0;
}

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;
}```

### Problem solution in 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();
});

return inputString[currentLine++];
}

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

constructor() {
this.tail = null;
}

};

while (node != null) {
ws.write(String(node.data));

node = node.next;

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

// Complete the insertNodeAtHead function below.

/*
*
*     int data;
* }
*
*/
}
return node;
}

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

for (let i = 0; i < llistCount; i++) {
}