[Solved] Delete a Node solution in Hackerrank - Hacerrank solution C, C++, java,js, Python

Algorithm

Problem Name: Data Structures - Delete a Node

Problem Link: https://www.hackerrank.com/challenges/delete-a-node-from-a-linked-list/problem?isFullScreen=true

In this HackerRank in Data Structures - Delete a Node solutions

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

llist = 0 -> 1 -> 2 -> 3

position = 2

After removing the node at position 2, llist' = 0 -> 1 -> 2

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

Constraints

1 <= n <= 1000
1 <= list[i] <= 1000, where list[i] is the i**th element of the linked list.

Sample Input

Sample Output

20 6 2 7 4 15 9

Explanation

The original list is 20 -> 6 -> 2 -> 19 -> 7 -> 4 -> 15 -> 9. After deleting the node at position 3, After deleting the node at position

20 -> 6 -> 2 -> 7 -> 4 -> 15 -> 9

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* tail;
};

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

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

    return node;
}

void insert_node_into_singly_linked_list(SinglyLinkedList** singly_linked_list, int node_data) {
    SinglyLinkedListNode* node = create_singly_linked_list_node(node_data);

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

    (*singly_linked_list)->tail = 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 '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* llist, int position) {
    if((position) == 0) {
        return llist->next;
    }
    llist->next = deleteNode(llist->next, position-1);
    return llist;
}

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

    SinglyLinkedList* llist = malloc(sizeof(SinglyLinkedList));
    llist->head = NULL;
    llist->tail = 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); }

        insert_node_into_singly_linked_list(&llist, llist_item);
    }

    char* position_endptr;
    char* position_str = readline();
    int position = strtol(position_str, &position_endptr, 10);

    if (position_endptr == position_str || *position_endptr != '\0') { exit(EXIT_FAILURE>; }

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

    char *sep = " ";

    print_singly_linked_list(llist1, sep, fptr);
    fprintf(fptr, "\n");

    free_singly_linked_list(llist1);

    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; }

        size_t new_length = alloc_length << 1;
        data = realloc(data, new_length);

        if (!data) { break; }

        alloc_length = new_length;
    }

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

    data = realloc(data, data_length);

    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;
        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* newhead = head->next;
        delete head;
        head = newhead;
        return head;
    }
    else {
        SinglyLinkedListNode* beforeDelete = head;
        for (int i=0; i < position-1; i++) {
            beforeDelete = beforeDelete->next;
        }
        SinglyLinkedListNode* del = beforeDelete->next;
        beforeDelete->next = del->next;
        delete del;
        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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#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 SinglyLinkedListNode tail;

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

        public void insertNode(int nodeData) {
            SinglyLinkedListNode node = new SinglyLinkedListNode(nodeData);

            if (this.head == null) {
                this.head = node;
            } else {
                this.tail.next = node;
            }

            this.tail = node;
        }
    }

    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 deleteNode(SinglyLinkedListNode head, int position) {
        if(position == 0){
            head = head.next;
            return head;
        }
        int k = position-1;
        SinglyLinkedListNode temp = head;
        while(k != 0){
            temp = temp.next;
            k--;
        }
        temp.next = temp.next.next;
        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])?");

            llist.insertNode(llistItem);
        }

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

        SinglyLinkedListNode llist1 = deleteNode(llist.head, position);

        printSinglyLinkedList(llist1, " ", 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', _ => {
    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;
        this.tail = null;
    }

    insertNode(nodeData) {
        const node = new SinglyLinkedListNode(nodeData);

        if (this.head == null) {
            this.head = node;
        } else {
            this.tail.next = node;
        }

        this.tail = node;
    }
};

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

        node = node.next;

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

/*
 * 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;
 * }
 *
 */

function deleteNode(head, position) {
    if (position == 0) {
        return head = head.next;
    }
    
    var newnode = head;
    
    // traverse to node
    for (var pos = 1; pos  <  position; pos++) {
        newnode = newnode.next;
    }
    newnode.next = newnode.next.next;
    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);
        llist.insertNode(llistItem);
    }

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

    let llist1 = deleteNode(llist.head, position);

    printSinglyLinkedList(llist1, " ", ws)
    ws.write("\n");

    ws.end();
}

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#5 Code Example with Python Programming

Code - Python Programming


#!/bin/python3

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
        self.tail = None

    def insert_node(self, node_data):
        node = SinglyLinkedListNode(node_data)

        if not self.head:
            self.head = node
        else:
            self.tail.next = node


        self.tail = node

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

        node = node.next

        if node:
            fptr.write(sep)

def deleteNode(head, position):
    if position == 0:
        return head.next
    current = head
    for i in range(position-1):
        current = current.next
    current.next = current.next.next
    
    return head

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

    llist_count = int(input())

    llist = SinglyLinkedList()

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

    position = int(input())

    llist1 = deleteNode(llist.head, position)

    print_singly_linked_list(llist1, ' ', fptr)
    fptr.write('\n')

    fptr.close()

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Demonstration

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