Given a singly linked list, a position and an element, the task is to write a program to insert that element in a linked list at a given position.
Examples:
Input: 3->5->8->10, data = 2, position = 2
Output: 3->2->5->8->10Input: 3->5->8->10, data = 11, position = 5
Output: 3->5->8->10->11
Approach: To insert a given data at a specified position, the below algorithm is to be followed:
- Traverse the Linked list upto position-1 nodes.
- Once all the position-1 nodes are traversed, allocate memory and the given data to the new node.
- Point the next pointer of the new node to the next of current node.
- Point the next pointer of current node to the new node.
Below is the implementation of the above algorithm.
C++
// C++ program for insertion in a single linked // list at a specified position #include <bits/stdc++.h> using namespace std; // A linked list Node struct Node { int data; struct Node* next; }; // Size of linked list int size = 0; // function to create and return a Node Node* getNode(int data) { // allocating space Node* newNode = new Node(); // inserting the required data newNode->data = data; newNode->next = NULL; return newNode; } // function to insert a Node at required position void insertPos(Node** current, int pos, int data) { // This condition to check whether the // position given is valid or not. if (pos < 1 || pos > size + 1) cout << "Invalid position!" << endl; else { // Keep looping until the pos is zero while (pos--) { if (pos == 0) { // adding Node at required position Node* temp = getNode(data); // Making the new Node to point to // the old Node at the same position temp->next = *current; // Changing the pointer of the Node previous // to the old Node to point to the new Node *current = temp; } else // Assign double pointer variable to point to the // pointer pointing to the address of next Node current = &(*current)->next; } size++; } } // This function prints contents // of the linked list void printList(struct Node* head) { while (head != NULL) { cout << " " << head->data; head = head->next; } cout << endl; } // Driver Code int main() { // Creating the list 3->5->8->10 Node* head = NULL; head = getNode(3); head->next = getNode(5); head->next->next = getNode(8); head->next->next->next = getNode(10); size = 4; cout << "Linked list before insertion: "; printList(head); int data = 12, pos = 3; insertPos(&head, pos, data); cout << "Linked list after insertion of 12 at position 3: "; printList(head); // front of the linked list data = 1, pos = 1; insertPos(&head, pos, data); cout << "Linked list after insertion of 1 at position 1: "; printList(head); // insertion at end of the linked list data = 15, pos = 7; insertPos(&head, pos, data); cout << "Linked list after insertion of 15 at position 7: "; printList(head); return 0; } |
Java
// Java program for insertion in a single linked // list at a specified position class GFG { // A linked list Node static class Node { public int data; public Node nextNode; // inserting the required data public Node(int data) { this.data = data; } } // function to create and return a Node static Node GetNode(int data) { return new Node(data); } // function to insert a Node at required position static Node InsertPos(Node headNode, int position, int data) { Node head = headNode; if (position < 1) System.out.print("Invalid position"); // if position is 1 then new node is // set infornt of head node // head node is changing. if (position == 1) { Node newNode = new Node(data); newNode.nextNode = headNode; head = newNode; } else { while (position-- != 0) { if (position == 1) { // adding Node at required position Node newNode = GetNode(data); // Making the new Node to point to // the old Node at the same position newNode.nextNode = headNode.nextNode; // Replacing current with new Node // to the old Node to point to the new Node headNode.nextNode = newNode; break; } headNode = headNode.nextNode; } if (position != 1) System.out.print("Position out of range"); } return head; } static void PrintList(Node node) { while (node != null) { System.out.print(node.data); node = node.nextNode; if (node != null) System.out.print(","); } System.out.println(); } // Driver code public static void main(String[] args) { Node head = GetNode(3); head.nextNode = GetNode(5); head.nextNode.nextNode = GetNode(8); head.nextNode.nextNode.nextNode = GetNode(10); System.out.print("Linked list before insertion: "); PrintList(head); int data = 12, pos = 3; head = InsertPos(head, pos, data); System.out.print("Linked list after" + " insertion of 12 at position 3: "); PrintList(head); // front of the linked list data = 1; pos = 1; head = InsertPos(head, pos, data); System.out.print("Linked list after" + "insertion of 1 at position 1: "); PrintList(head); // insertion at end of the linked list data = 15; pos = 7; head = InsertPos(head, pos, data); System.out.print("Linked list after" + " insertion of 15 at position 7: "); PrintList(head); } } // This code is contributed by Rajput-Ji |
Python3
# Python3 program for insertion in a single linked # list at a specified position # A linked list Node class Node: def __init__(self, data): self.data = data self.nextNode = None # function to create and return a Node def getNode(data): # allocating space newNode = Node(data) return newNode; # function to insert a Node at required position def insertPos(headNode, position, data): head = headNode # This condition to check whether the # position given is valid or not. if (position < 1): print("Invalid position!") if position == 1: newNode = Node(data) newNode.nextNode = headNode head = newNode else: # Keep looping until the position is zero while (position != 0): position -= 1 if (position == 1): # adding Node at required position newNode = getNode(data) # Making the new Node to point to # the old Node at the same position newNode.nextNode = headNode.nextNode # Replacing headNode with new Node # to the old Node to point to the new Node headNode.nextNode = newNode break headNode = headNode.nextNode if headNode == None: break if position != 1: print("position out of range") return head # This function prints contents # of the linked list def printList(head): while (head != None): print(' ' + str(head.data), end = '') head = head.nextNode; print() # Driver Code if __name__=='__main__': # Creating the list 3.5.8.10 head = getNode(3); head.nextNode = getNode(5); head.nextNode.nextNode = getNode(8); head.nextNode.nextNode.nextNode = getNode(10); print("Linked list before insertion: ", end='') printList(head); data = 12 position = 3; head = insertPos(head, position, data); print("Linked list after insertion of 12 at position 3: ", end = '') printList(head); # front of the linked list data = 1 position = 1; head = insertPos(head, position, data); print("Linked list after insertion of 1 at position 1: ", end = '') printList(head); # insertion at end of the linked list data = 15 position = 7; head = insertPos(head, position, data); print("Linked list after insertion of 15 at position 7: ", end='') printList(head); # This code iscontributed by rutvik_56 |
C#
// C# program for insertion in a single linked // list at a specified position using System; namespace InsertIntoLinkedList { class Program { // A linked list Node private class Node { public int data; public Node nextNode; // inserting the required data public Node(int data) => this.data = data; } // function to create and return a Node static Node GetNode(int data) => new Node(data); // function to insert a Node at required position static Node InsertPos(Node headNode, int position, int data) { var head = headNode; if (position < 1) Console.WriteLine("Invalid position"); //if position is 1 then new node is // set infornt of head node //head node is changing. if (position == 1) { var newNode = new Node(data); newNode.nextNode = headNode; head = newNode; } else { while (position-- != 0) { if (position == 1) { // adding Node at required position Node newNode = GetNode(data); // Making the new Node to point to // the old Node at the same position newNode.nextNode = headNode.nextNode; // Replacing current with new Node // to the old Node to point to the new Node headNode.nextNode = newNode; break; } headNode = headNode.nextNode; } if (position != 1) Console.WriteLine("Position out of range"); } return head; } static void PrintList(Node node) { while (node != null) { Console.Write(node.data); node = node.nextNode; if(node != null) Console.Write(","); } Console.WriteLine(); } // Driver code static void Main(string[] args) { var head = GetNode(3); head.nextNode = GetNode(5); head.nextNode.nextNode = GetNode(8); head.nextNode.nextNode.nextNode = GetNode(10); Console.WriteLine("Linked list before insertion: "); PrintList(head); int data = 12, pos = 3; head = InsertPos(head, pos, data); Console.WriteLine("Linked list after" + " insertion of 12 at position 3: "); PrintList(head); // front of the linked list data = 1; pos = 1; head = InsertPos(head, pos, data); Console.WriteLine("Linked list after" + "insertion of 1 at position 1: "); PrintList(head); // insertion at end of the linked list data = 15; pos = 7; head = InsertPos(head, pos, data); Console.WriteLine("Linked list after" + " insertion of 15 at position 7: "); PrintList(head); } } } // This code is contributed by dhirucoool |
Javascript
<script> // javascript program for insertion in a single linked // list at a specified position // A linked list Node class Node { // inserting the required data constructor(val) { this.data = val; this.nextNode = null; } } // function to create and return a Node function GetNode(data) { return new Node(data); } // function to insert a Node at required position function InsertPos( headNode , position , data) { head = headNode; if (position < 1) document.write("Invalid position"); // if position is 1 then new node is // set infront of head node // head node is changing. if (position == 1) { newNode = new Node(data); newNode.nextNode = headNode; head = newNode; } else { while (position-- != 0) { if (position == 1) { // adding Node at required position newNode = GetNode(data); // Making the new Node to point to // the old Node at the same position newNode.nextNode = headNode.nextNode; // Replacing current with new Node // to the old Node to point to the new Node headNode.nextNode = newNode; break; } headNode = headNode.nextNode; } if (position != 1) document.write("Position out of range"); } return head; } function PrintList( node) { while (node != null) { document.write(node.data); node = node.nextNode; if (node != null) document.write(","); } document.write("<br/>"); } // Driver code head = GetNode(3); head.nextNode = GetNode(5); head.nextNode.nextNode = GetNode(8); head.nextNode.nextNode.nextNode = GetNode(10); document.write("Linked list before insertion: "); PrintList(head); var data = 12, pos = 3; head = InsertPos(head, pos, data); document.write("Linked list after" + " insertion of 12 at position 3: "); PrintList(head); // front of the linked list data = 1; pos = 1; head = InsertPos(head, pos, data); document.write("Linked list after" + "insertion of 1 at position 1: "); PrintList(head); // insertion at end of the linked list data = 15; pos = 7; head = InsertPos(head, pos, data); document.write("Linked list after" + " insertion of 15 at position 7: "); PrintList(head); // This code is contributed by gauravrajput1. </script> |
Time Complexity: O(N)
Auxiliary Space: O(1)
Feeling lost in the world of random DSA topics, wasting time without progress? It’s time for a change! Join our DSA course, where we’ll guide you on an exciting journey to master DSA efficiently and on schedule.
Ready to dive in? Explore our Free Demo Content and join our DSA course, trusted by over 100,000 neveropen!
Ready to dive in? Explore our Free Demo Content and join our DSA course, trusted by over 100,000 neveropen!
