# Insertion in a sorted circular linked list when a random pointer is given

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[] in the circular linked list.

Examples:

Input: arr[] = {12, 56, 2, 11, 1, 90}
Output: 1 2 11 12 56 90

Input: arr[] = {6, 2, 78, 45, 200}
Output: 2 6 45 78 200

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

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.

• Find the last node of 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 ` `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 `

 `// 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 `

Output:
```1 2 11 12 56 90
```

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Third year Department of Information Technology Jadavpur University

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