Algorithm
Problem Name: Data Structures -
In this HackerRank in Data Structures -
You are given the pointer to the head node of a sorted linked list, where the data in the nodes is in ascending order. Delete nodes and return a sorted list with each distinct value in the original list. The given head pointer may be null indicating that the list is empty.
Example
head refers to the first node in the list.
1 -> 2 -> 2 -> 3 -> 3 -> 3 -> 3 ->NULL
Remove 1 of the 2 data values and return head pointing to the revised list 1 -> 2 -> 3 -> NULL
Function Description
Complete the removeDuplicates function in the editor below.
removeDuplicates has the following parameter:
- SinglyLinkedListNode pointer head: a reference to the head of the list
Returns
- SinglyLinkedListNode pointer: a reference to the head of the revised list
Input Format
The first line contains an integer t, the number of test cases.
The format for each test case is as follows:
The first line contains an integer n, the number of elements in the linked list.
Each of the next n lines contains an integer, the data value for each of the elements of the linked list.
Constraints
- 1 <= t <= 10
- 1 <= n <= 1000
- 1 <= list[i] <= 1000
Sample Input
STDIN Function
----- --------
1 t = 1
5 n = 5
1 data values = 1, 2, 2, 3, 4
2
2
3
4
Sample Output
1 2 3 4
Explanation
The final linked list is: 1 -> 2 -> 3 -> 4 -> NULL
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 'removeDuplicates' function below.
*
* The function is expected to return an INTEGER_SINGLY_LINKED_LIST.
* The function accepts INTEGER_SINGLY_LINKED_LIST llist as parameter.
*/
/*
* For your reference:
*
* SinglyLinkedListNode {
* int data;
* SinglyLinkedListNode* next;
* };
*
*/
SinglyLinkedListNode* removeDuplicates(SinglyLinkedListNode* head) {
if(head == NULL) return head;
SinglyLinkedListNode* currBoi = head;
SinglyLinkedListNode* nextBoi = currBoi->next;
while(nextBoi != NULL){
if(currBoi->data == nextBoi->data){
SinglyLinkedListNode* temp = nextBoi;
nextBoi = nextBoi->next;
currBoi->next = nextBoi;
temp->next = NULL;
free(temp);
} else {
currBoi = currBoi->next;
nextBoi = nextBoi->next;
}
}
return head;
}
int main()
{
FILE* fptr = fopen(getenv("OUTPUT_PATH"), "w");
char* t_endptr;
char* t_str = readline();
int t = strtol(t_str, &t_endptr, 10);
if (t_endptr == t_str || *t_endptr != '\0') { exit(EXIT_FAILURE); }
for (int t_itr = 0; t_itr < t; t_itr++) {
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);
}
SinglyLinkedListNode* llist1 = removeDuplicates(llist->head);
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;
}
#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);
}
}
SinglyLinkedListNode* removeDuplicates(SinglyLinkedListNode* llist) {
SinglyLinkedListNode *curr = llist;
while (curr != NULL) {
SinglyLinkedListNode *next = curr->next;
while (next != NULL && next->data == curr->data)
next = next->next;
curr->next = next;
curr = next;
if (next != NULL) next = next->next;
}
return llist;
}
int main()
{
ofstream fout(getenv("OUTPUT_PATH"));
int t;
cin >> t;
cin.ignore(numeric_limits < streamsize>::max(), '\n');
for (int t_itr = 0; t_itr < t; t_itr++) {
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);
}
SinglyLinkedListNode* llist1 = removeDuplicates(llist->head);
print_singly_linked_list(llist1, " ", fout);
fout << "\n";
free_singly_linked_list(llist1);
}
fout.close();
return 0;
}
#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);
}
}
}
public static SinglyLinkedListNode removeDuplicates(SinglyLinkedListNode llist) {
// Write your code here
SinglyLinkedListNode temp = llist;
while(temp.next!=null)
{
if(temp.data == temp.next.data)
{
temp.next = temp.next.next;
}
else
{
temp = temp.next;
}
}
return llist;
}
class Result {
}
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 t = scanner.nextInt();
scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");
for (int tItr = 0; tItr < t; tItr++) {
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);
}
SinglyLinkedListNode llist1 = removeDuplicates(llist.head);
printSinglyLinkedList(llist1, " ", bufferedWriter);
bufferedWriter.newLine();
}
bufferedWriter.close();
scanner.close(>;
}
}
#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 'removeDuplicates' function below.
*
* The function is expected to return an INTEGER_SINGLY_LINKED_LIST.
* The function accepts INTEGER_SINGLY_LINKED_LIST llist as parameter.
*/
/*
* For your reference:
*
* SinglyLinkedListNode {
* int data;
* SinglyLinkedListNode next;
* }
*
*/
function removeDuplicates(head) {
if (!head) return head;
var node = head;
while (node) {
if (node.next && node.data === node.next.data) {
node.next = node.next.next;
} else {
node = node.next;
}
}
return head;
}
function main() {
const ws = fs.createWriteStream(process.env.OUTPUT_PATH);
const t = parseInt(readLine(), 10);
for (let tItr = 0; tItr < t; tItr++) {
const llistCount = parseInt(readLine(), 10);
let llist = new SinglyLinkedList();
for (let i = 0; i < llistCount; i++) {
const llistItem = parseInt(readLine(), 10);
llist.insertNode(llistItem);
}
let llist1 = removeDuplicates(llist.head);
printSinglyLinkedList(llist1, " ", ws)
ws.write("\n");
}
ws.end();
}
#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)
#
# Complete the 'removeDuplicates' function below.
#
# The function is expected to return an INTEGER_SINGLY_LINKED_LIST.
# The function accepts INTEGER_SINGLY_LINKED_LIST llist as parameter.
#
#
# For your reference:
#
# SinglyLinkedListNode:
# int data
# SinglyLinkedListNode next
#
#
def removeDuplicates(head):
ans=None
s=set()
ansl=SinglyLinkedList()
while head:
if head.data not in s:
s.add(head.data)
ansl.insert_node(head.data)
head=head.next
else:
head=head.next
return ansl.head
if __name__ == '__main__':
fptr = open(os.environ['OUTPUT_PATH'], 'w')
t = int(input())
for t_itr in range(t):
llist_count = int(input())
llist = SinglyLinkedList()
for _ in range(llist_count):
llist_item = int(input())
llist.insert_node(llist_item)
llist1 = removeDuplicates(llist.head)
print_singly_linked_list(llist1, ' ', fptr)
fptr.write('\n')
fptr.close()