Sort Linked List containing values from 1 to N
Last Updated :
22 Dec, 2023
Given a linked list of size N containing all values from 1 to N. The task is to sort the linked list in increasing order.
Examples:
Input : List = 3 -> 5 -> 4 -> 6 -> 1 -> 2
Output : 1 -> 2 -> 3 -> 4 -> 5 -> 6
Input : List = 5 -> 4 -> 3 -> 2 -> 1
Output : 1 -> 2 -> 3 -> 4 -> 5
Naive approach: The simplest approach is to sort this linked list with the use of any type of sorting method. It takes O(N*logN) minimum time.
Efficient approach: An efficient approach is to observe that the linked list contains a total of N elements and elements are numbered from 1 to N. Traverse the linked list and replace every element with its position.
Below is the implementation of this approach:
C++
#include <iostream>
using namespace std;
struct Node {
int data;
struct Node* next;
};
void sortList(struct Node* head) {
struct Node* current = head;
struct Node* index = nullptr;
int temp;
while (current != nullptr) {
index = current->next;
while (index != nullptr) {
if (current->data > index->data) {
temp = current->data;
current->data = index->data;
index->data = temp;
}
index = index->next;
}
current = current->next;
}
}
void push(struct Node** head_ref, int new_data) {
struct Node* new_node = new Node();
new_node->data = new_data;
new_node->next = (*head_ref);
(*head_ref) = new_node;
}
void printList(struct Node* node) {
while (node != nullptr) {
cout << node->data << " ";
node = node->next;
}
}
int main() {
struct Node* start = nullptr;
push(&start, 2);
push(&start, 1);
push(&start, 6);
push(&start, 4);
push(&start, 5);
push(&start, 3);
sortList(start);
cout << "Sorted Linked List: ";
printList(start);
return 0;
}
|
Java
import java.util.*;
class GFG {
static class Node {
int data;
Node next;
}
static Node start;
static Node sortList(Node head) {
Node current, index = null;
int temp;
if (head == null) {
return null;
} else {
for (current = head; current.next != null; current = current.next) {
for (index = current.next; index != null; index = index.next) {
if (current.data > index.data) {
temp = current.data;
current.data = index.data;
index.data = temp;
}
}
}
}
return head;
}
static Node push(Node head_ref, int new_data) {
Node new_node = new Node();
new_node.data = new_data;
new_node.next = head_ref;
head_ref = new_node;
start = head_ref;
return head_ref;
}
static void printList(Node node) {
while (node != null) {
System.out.print(node.data + " ");
node = node.next;
}
}
public static void main(String[] args) {
start = null;
start = push(start, 2);
start = push(start, 1);
start = push(start, 6);
start = push(start, 4);
start = push(start, 5);
start = push(start, 3);
start = sortList(start);
printList(start);
}
}
|
Python3
class Node:
def __init__(self):
self.data = 0
self.next = None
def sort_list(head):
current = head
while current is not None:
index = current.next
while index is not None:
if current.data > index.data:
temp = current.data
current.data = index.data
index.data = temp
index = index.next
current = current.next
def push(head_ref, new_data):
new_node = Node()
new_node.data = new_data
new_node.next = head_ref
return new_node
def print_list(node):
while node is not None:
print(node.data, end=" ")
node = node.next
if __name__ == "__main__":
start = None
start = push(start, 2)
start = push(start, 1)
start = push(start, 6)
start = push(start, 4)
start = push(start, 5)
start = push(start, 3)
sort_list(start)
print("Sorted Linked List:", end=" ")
print_list(start)
|
C#
using System;
public class Node
{
public int data;
public Node next;
}
public class Program
{
public static void SortList(Node head)
{
Node current = head;
Node index = null;
int temp;
while (current != null)
{
index = current.next;
while (index != null)
{
if (current.data > index.data)
{
temp = current.data;
current.data = index.data;
index.data = temp;
}
index = index.next;
}
current = current.next;
}
}
public static Node Push(Node headRef, int newData)
{
Node newNode = new Node();
newNode.data = newData;
newNode.next = headRef;
return newNode;
}
public static void PrintList(Node node)
{
while (node != null)
{
Console.Write(node.data + " ");
node = node.next;
}
}
public static void Main()
{
Node start = null;
start = Push(start, 9);
start = Push(start, 1);
start = Push(start, 6);
start = Push(start, 4);
start = Push(start, 5);
start = Push(start, 3);
SortList(start);
Console.Write("Sorted Linked List: ");
PrintList(start);
}
}
|
Javascript
class Node {
constructor() {
this.data = 0;
this.next = null;
}
}
function sortList(head) {
let current = head;
let index = null;
let temp;
while (current !== null) {
index = current.next;
while (index !== null) {
if (current.data > index.data) {
temp = current.data;
current.data = index.data;
index.data = temp;
}
index = index.next;
}
current = current.next;
}
}
function push(headRef, newData) {
const newNode = new Node();
newNode.data = newData;
newNode.next = headRef;
return newNode;
}
function printList(node) {
while (node !== null) {
console.log(node.data + " ");
node = node.next;
}
}
let start = null;
start = push(start, 2);
start = push(start, 1);
start = push(start, 6);
start = push(start, 4);
start = push(start, 5);
start = push(start, 3);
sortList(start);
console.log("Sorted Linked List: ");
printList(start);
|
Complexity Analysis:
- Time Complexity: O(n)
- Auxiliary Space: O(1)
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