Insertion in a sorted circular linked list when a random pointer is given
Last Updated :
22 Jun, 2022
Improve
Given an array arr[] of integers and a pointer to a random node of a circular sorted linked list (initially empty), the task is to insert all the elements of arr[] into the circular linked list.
Examples:
Input: arr[] = {12, 56, 2, 11, 1, 90}
Output: 1 2 11 12 56 90Input: arr[] = {6, 2, 78, 45, 200}
Output: 2 6 45 78 200
Approach: We are given a random pointer to a node in the circular linked list and we have to find the head of the circular linked list to insert the node in a sorted linked list.
Insertion in a sorted linked list when the head is given is explained in this article.
To find the head of the circular sorted linked list:
- Find the last node of the linked list (the last node will be greater than its successor i.e. first element.
- Once the head of the linked list is found, then the elements can be inserted using the same approach which is discussed in the previous article.
Below is the implementation of the above approach:
// C++ implementation of the approach
#include <bits/stdc++.h>
using namespace std;
// Node structure
struct Node {
Node* next;
int data;
};
// Function to create a node
Node* create()
{
Node* new_node = (Node*)malloc(sizeof(Node));
new_node->next = NULL;
return new_node;
}
// Function to find and return the head
Node* find_head(Node* random)
{
// If the list is empty
if (random == NULL)
return NULL;
Node *head, *var = random;
// Finding the last node of the linked list
// the last node must have the highest value
// if no such element is present then all the nodes
// of the linked list must be same
while (!(var->data > var->next->data || var->next == random)) {
var = var->next;
}
// Return the head
return var->next;
}
// Function to insert a new_node in the list in sorted fashion
// Note that this function expects a pointer to head node
// as this can modify the head of the input linked list
Node* sortedInsert(Node* head_ref, Node* new_node)
{
Node* current = head_ref;
// If the list is empty
if (current == NULL) {
new_node->next = new_node;
head_ref = new_node;
}
// If the node to be inserted is the smallest
// then it has to be the new head
else if (current->data >= new_node->data) {
// Find the last node of the list as it
// will be pointing to the head
while (current->next != head_ref)
current = current->next;
current->next = new_node;
new_node->next = head_ref;
head_ref = new_node;
}
else {
// Locate the node before the point of insertion
while (current->next != head_ref
&& current->next->data < new_node->data) {
current = current->next;
}
new_node->next = current->next;
current->next = new_node;
}
// Return the new head
return head_ref;
}
// Function to print the nodes of the linked list
void printList(Node* start)
{
Node* temp;
if (start != NULL) {
temp = start;
do {
cout << temp->data << " ";
temp = temp->next;
} while (temp != start);
}
}
// Driver code
int main()
{
int arr[] = { 12, 56, 2, 11, 1, 90 };
int list_size, i;
// Start with an empty linked list
Node* start = NULL;
Node* temp;
// Create linked list from the given array
for (i = 0; i < 6; i++) {
// Move to a random node if it exists
if (start != NULL)
for (int j = 0; j < (rand() % 10); j++)
start = start->next;
temp = create();
temp->data = arr[i];
start = sortedInsert(find_head(start), temp);
}
// Print the contents of the created list
printList(find_head(start));
return 0;
}
// Java implementation of the approach
import java.util.*;
import java.lang.*;
import java.io.*;
class GFG
{
// Node structure
static class Node
{
Node next;
int data;
};
// Function to create a node
static Node create()
{
Node new_node = new Node();
new_node.next = null;
return new_node;
}
// Function to find and return the head
static Node find_head(Node random)
{
// If the list is empty
if (random == null)
return null;
Node head, var = random;
// Finding the last node of the linked list
// the last node must have the highest value
// if no such element is present then all the nodes
// of the linked list must be same
while (!(var.data > var.next.data ||
var.next == random))
{
var = var.next;
}
// Return the head
return var.next;
}
// Function to insert a new_node in the list
// in sorted fashion. Note that this function
// expects a pointer to head node as this can
// modify the head of the input linked list
static Node sortedInsert(Node head_ref,
Node new_node)
{
Node current = head_ref;
// If the list is empty
if (current == null)
{
new_node.next = new_node;
head_ref = new_node;
}
// If the node to be inserted is the smallest
// then it has to be the new head
else if (current.data >= new_node.data)
{
// Find the last node of the list as it
// will be pointing to the head
while (current.next != head_ref)
current = current.next;
current.next = new_node;
new_node.next = head_ref;
head_ref = new_node;
}
else
{
// Locate the node before the point of insertion
while (current.next != head_ref &&
current.next.data < new_node.data)
{
current = current.next;
}
new_node.next = current.next;
current.next = new_node;
}
// Return the new head
return head_ref;
}
// Function to print the nodes of the linked list
static void printList(Node start)
{
Node temp;
if (start != null)
{
temp = start;
do
{
System.out.print(temp.data + " ");
temp = temp.next;
} while (temp != start);
}
}
// Driver code
public static void main(String args[])
{
int arr[] = { 12, 56, 2, 11, 1, 90 };
int list_size, i;
// Start with an empty linked list
Node start = null;
Node temp;
// Create linked list from the given array
for (i = 0; i < 6; i++)
{
// Move to a random node if it exists
if (start != null)
for (int j = 0;
j < (Math.random() * 10); j++)
start = start.next;
temp = create();
temp.data = arr[i];
start = sortedInsert(find_head(start), temp);
}
// Print the contents of the created list
printList(find_head(start));
}
}
// This code is contributed by Arnab Kundu
# Python3 implementation of the approach
from random import randint
# Node structure
class Node:
def __init__(self):
self.next = None
self.data = 0
# Function to create a node
def create():
new_node = Node()
new_node.next = None
return new_node
# Function to find and return the head
def find_head(random):
# If the list is empty
if (random == None):
return None
head = None
var = random
# Finding the last node of the linked list
# the last node must have the highest value
# if no such element is present then all
# the nodes of the linked list must be same
while (not(var.data > var.next.data or
var.next == random)):
var = var.next
# Return the head
return var.next
# Function to insert a new_node in the list in
# sorted fashion. Note that this function expects
# a pointer to head node as this can modify the
# head of the input linked list
def sortedInsert(head_ref, new_node):
current = head_ref
# If the list is empty
if (current == None):
new_node.next = new_node
head_ref = new_node
# If the node to be inserted is the smallest
# then it has to be the new head
elif (current.data >= new_node.data):
# Find the last node of the list as it
# will be pointing to the head
while (current.next != head_ref):
current = current.next
current.next = new_node
new_node.next = head_ref
head_ref = new_node
else:
# Locate the node before the point of insertion
while (current.next != head_ref and
current.next.data < new_node.data):
current = current.next
new_node.next = current.next
current.next = new_node
# Return the new head
return head_ref
# Function to print the nodes of the linked list
def printList(start):
temp = 0
if (start != None):
temp = start
while True:
print(temp.data, end = ' ')
temp = temp.next
if (temp == start):
break
# Driver code
if __name__=='__main__':
arr = [ 12, 56, 2, 11, 1, 90 ]
# Start with an empty linked list
start = None;
temp = 0
# Create linked list from the given array
for i in range(6):
# Move to a random node if it exists
if (start != None):
for j in range(randint(0, 10)):
start = start.next
temp = create()
temp.data = arr[i]
start = sortedInsert(find_head(start), temp)
# Print the contents of the created list
printList(find_head(start))
# This code is contributed by rutvik_56
// C# implementation of the approach
using System;
class GFG
{
// Node structure
public class Node
{
public Node next;
public int data;
};
// Function to create a node
static Node create()
{
Node new_node = new Node();
new_node.next = null;
return new_node;
}
// Function to find and return the head
static Node find_head(Node random)
{
// If the list is empty
if (random == null)
return null;
Node var = random;
// Finding the last node of the linked list
// the last node must have the highest value
// if no such element is present then all the nodes
// of the linked list must be same
while (!(var.data > var.next.data ||
var.next == random))
{
var = var.next;
}
// Return the head
return var.next;
}
// Function to insert a new_node in the list
// in sorted fashion. Note that this function
// expects a pointer to head node as this can
// modify the head of the input linked list
static Node sortedInsert(Node head_ref,
Node new_node)
{
Node current = head_ref;
// If the list is empty
if (current == null)
{
new_node.next = new_node;
head_ref = new_node;
}
// If the node to be inserted is the smallest
// then it has to be the new head
else if (current.data >= new_node.data)
{
// Find the last node of the list as it
// will be pointing to the head
while (current.next != head_ref)
current = current.next;
current.next = new_node;
new_node.next = head_ref;
head_ref = new_node;
}
else
{
// Locate the node before the point of insertion
while (current.next != head_ref &&
current.next.data < new_node.data)
{
current = current.next;
}
new_node.next = current.next;
current.next = new_node;
}
// Return the new head
return head_ref;
}
// Function to print the nodes of the linked list
static void printList(Node start)
{
Node temp;
if (start != null)
{
temp = start;
do
{
Console.Write(temp.data + " ");
temp = temp.next;
} while (temp != start);
}
}
// Driver code
public static void Main(String []args)
{
int []arr = { 12, 56, 2, 11, 1, 90 };
int i;
// Start with an empty linked list
Node start = null;
Node temp;
// Create linked list from the given array
for (i = 0; i < 6; i++)
{
// Move to a random node if it exists
if (start != null)
for (int j = 0;
j < (new Random().Next() * 10); j++)
start = start.next;
temp = create();
temp.data = arr[i];
start = sortedInsert(find_head(start), temp);
}
// Print the contents of the created list
printList(find_head(start));
}
}
// This code is contributed by PrinciRaj1992
<script>
// javascript implementation of the approach
// Node structure
class Node {
constructor(val) {
this.data = val;
this.next = null;
}
}
// Function to create a node
function create() {
var new_node = new Node();
new_node.next = null;
return new_node;
}
// Function to find and return the head
function find_head(random) {
// If the list is empty
if (random == null)
return null;
var head ,vari = random;
// Finding the last node of the linked list
// the last node must have the highest value
// if no such element is present then all the nodes
// of the linked list must be same
while (!(vari.data > vari.next.data ||
vari.next == random)) {
vari = vari.next;
}
// Return the head
return vari.next;
}
// Function to insert a new_node in the list
// in sorted fashion. Note that this function
// expects a pointer to head node as this can
// modify the head of the input linked list
function sortedInsert(head_ref, new_node) {
var current = head_ref;
// If the list is empty
if (current == null) {
new_node.next = new_node;
head_ref = new_node;
}
// If the node to be inserted is the smallest
// then it has to be the new head
else if (current.data >= new_node.data) {
// Find the last node of the list as it
// will be pointing to the head
while (current.next != head_ref)
current = current.next;
current.next = new_node;
new_node.next = head_ref;
head_ref = new_node;
}
else {
// Locate the node before the point of insertion
while (current.next != head_ref &&
current.next.data < new_node.data) {
current = current.next;
}
new_node.next = current.next;
current.next = new_node;
}
// Return the new head
return head_ref;
}
// Function to print the nodes of the linked list
function printList(start) {
var temp;
if (start != null) {
temp = start;
do {
document.write(temp.data + " ");
temp = temp.next;
} while (temp != start);
}
}
// Driver code
var arr = [ 12, 56, 2, 11, 1, 90 ];
var list_size, i;
// Start with an empty linked list
var start = null;
var temp;
// Create linked list from the given array
for (i = 0; i < 6; i++) {
// Move to a random node if it exists
if (start != null)
for (j = 0; j < (Math.random() * 10); j++)
start = start.next;
temp = create();
temp.data = arr[i];
start = sortedInsert(find_head(start), temp);
}
// Print the contents of the created list
printList(find_head(start));
// This code is contributed by todaysgaurav
</script>
Output:
1 2 11 12 56 90
Time Complexity: O(N)
Auxiliary Space: O(N)
