Given a singly linked list containing N nodes, the task is to delete all nodes from the list which are not prime.
Examples:
Input : List = 15 -> 16 -> 6 -> 7 -> 17
Output : Final List = 7 -> 17Input : List = 15 -> 3 -> 4 -> 2 -> 9
Output : Final List = 3 ->2
Approach: The idea is to traverse the nodes of the singly linked list one by one and get the pointer of the nodes which are not prime. Delete those nodes by following the approach used in the post: Delete a node from Linked List.
Below is the implementation of above idea:
C++
// C++ implementation to delete all// non-prime nodes from the singly// linked list#include <bits/stdc++.h>using namespace std;// Node of the singly linked liststruct Node { int data; Node* next;};// function to insert a node at the beginning// of the singly Linked Listvoid 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;}// Function to check if a number is primebool isPrime(int n){ // Corner cases if (n <= 1) return false; if (n <= 3) return true; // This is checked so that we can skip // middle five numbers in below loop if (n % 2 == 0 || n % 3 == 0) return false; for (int i = 5; i * i <= n; i = i + 6) if (n % i == 0 || n % (i + 2) == 0) return false; return true;}// function to delete all non-prime nodes// from the singly linked listvoid deleteNonPrimeNodes(Node** head_ref){ // Remove all composite nodes at the beginning Node* ptr = *head_ref; while (ptr != NULL && !isPrime(ptr->data)) { Node* temp = ptr; ptr = ptr->next; delete (temp); } *head_ref = ptr; if (ptr == NULL) return; // Remove remaining nodes Node* curr = ptr->next; while (curr != NULL) { if (!isPrime(curr->data)) { ptr->next = curr->next; delete (curr); curr = ptr->next; } else { ptr = curr; curr = curr->next; } }}// function to print nodes in a// given singly linked listvoid printList(Node* head){ while (head != NULL) { cout << head->data << " "; head = head->next; }}// Driver programint main(){ // start with the empty list Node* head = NULL; // create the linked list // 15 -> 16 -> 7 -> 6 -> 17 push(&head, 17); push(&head, 7); push(&head, 6); push(&head, 16); push(&head, 15); cout << "Original List: "; printList(head); deleteNonPrimeNodes(&head); cout << "\nModified List: "; printList(head);} |
Java
// Java implementation to delete all// prime nodes from the singly// linked listimport java.util.*;// Node of the singly linked listclass Node { int data; Node next;}class GFG { // function to insert a node at the beginning // of the singly Linked List static void push(Node head_ref[], int new_data) { // allocate node Node new_node = new Node(); // put in the data new_node.data = new_data; // link the old list off the new node new_node.next = head_ref[0]; // move the head to point to the new node head_ref[0] = new_node; } // Function to check if a number is prime static boolean isPrime(int n) { // Corner Cases if (n <= 1) return false; if (n <= 3) return true; // This is checked so that we can skip // middle five numbers in below loop if (n % 2 == 0 || n % 3 == 0) return false; for (int i = 5; i * i <= n; i = i + 6) { if (n % i == 0 || n % (i + 2) == 0) return false; } return true; } // function to delete a node in a singly Linked List. // head_ref --> pointer to head node pointer. // del --> pointer to node to be deleted static void deleteNode(Node head_ref[], Node del) { // base case if (head_ref[0] == null || del == null) return; // If node to be deleted is head node if (head_ref[0] == del) { head_ref[0] = del.next; return; } // traverse list till not found // delete node Node temp = head_ref[0]; while (temp.next != del) { temp = temp.next; } // copy address of node temp.next = del.next; // Finally, free the memory occupied by del del = null; } // function to delete all prime nodes // from the singly linked list static void deletePrimeNodes(Node head_ref[]) { Node ptr = head_ref[0]; Node next; while (ptr != null) { next = ptr.next; // if true, delete node 'ptr' if (isPrime(ptr.data) == false) deleteNode(head_ref, ptr); ptr = next; } } // function to print nodes in a // given singly linked list static void printList(Node head) { while (head != null) { System.out.print(head.data + " "); head = head.next; } } // Driver Code public static void main(String[] args) { // start with the empty list Node[] head_ref = new Node[1]; head_ref[0] = null; // create the linked list // 15 -> 16 -> 7 -> 6 -> 17 push(head_ref, 17); push(head_ref, 7); push(head_ref, 6); push(head_ref, 16); push(head_ref, 15); System.out.print("Original List: "); printList(head_ref[0]); deletePrimeNodes(head_ref); System.out.print("\nModified List: "); printList(head_ref[0]); }}// this code is contributed by shubhamrajput6156 |
Python3
# Python3 implementation to delete all# non-prime nodes from the singly# linked listimport math# Node of the singly linked listclass Node: def __init__(self, data): self.data = data self.next = None# function to insert a node at the beginning# of the singly Linked Listdef push(head_ref, new_data): new_node = Node(new_data) new_node.data = new_data new_node.next = head_ref head_ref = new_node return head_ref# Function to check if a number is primedef isPrime(n): # Corner cases if (n <= 1): return False if (n <= 3): return True # This is checked so that we can skip # middle five numbers in below loop if (n % 2 == 0 or n % 3 == 0): return False for i in range(5, n + 1, 6): if (i * i < n + 2 and (n % i == 0 or n % (i + 2) == 0)): return False return True# function to delete all non-prime nodes# from the singly linked listdef deleteNonPrimeNodes(head_ref): # Remove all composite nodes at the beginning ptr = head_ref while (ptr != None and isPrime(ptr.data) != True): temp = ptr ptr = ptr.next # delete(temp) head_ref = ptr if (ptr == None): return None # Remove remaining nodes curr = ptr.next while (curr != None): if (isPrime(curr.data) != True): ptr.next = curr.next # delete(curr) curr = ptr.next else: ptr = curr curr = curr.next return head_ref# function to print nodes in a# given singly linked listdef printList(head): while (head != None): print(head.data, end=" ") head = head.next# Driver Codeif __name__ == '__main__': # start with the empty list head = None # create the linked list # 15 -> 16 -> 7 -> 6 -> 17 head = push(head, 17) head = push(head, 7) head = push(head, 6) head = push(head, 16) head = push(head, 15) print("Original List: ") printList(head) head = deleteNonPrimeNodes(head) print("\nModified List: ") printList(head)# This code is contributed by AbhiThakur |
C#
// C# implementation to delete all// non-prime nodes from the singly// linked listusing System;class GFG { // Node of the singly linked list public class Node { public int data; public Node next; }; // function to insert a node at the beginning // of the singly Linked List 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; return head_ref; } // Function to check if a number is prime static bool isPrime(int n) { // Corner cases if (n <= 1) { return false; } if (n <= 3) { return true; } // This is checked so that we can skip // middle five numbers in below loop if (n % 2 == 0 || n % 3 == 0) { return false; } for (int i = 5; i * i <= n; i = i + 6) { if (n % i == 0 || n % (i + 2) == 0) { return false; } } return true; } // function to delete all non-prime nodes // from the singly linked list static Node deleteNonPrimeNodes(Node head_ref) { // Remove all composite nodes // at the beginning Node ptr = head_ref; while (ptr != null && !isPrime(ptr.data)) { Node temp = ptr; ptr = ptr.next; } head_ref = ptr; if (ptr == null) { return null; } // Remove remaining nodes Node curr = ptr.next; while (curr != null) { if (!isPrime(curr.data)) { ptr.next = curr.next; curr = ptr.next; } else { ptr = curr; curr = curr.next; } } return head_ref; } // function to print nodes in a // given singly linked list static void printList(Node head) { while (head != null) { Console.Write(head.data + " "); head = head.next; } } // Driver code public static void Main(String[] args) { // start with the empty list Node head = null; // create the linked list // 15 . 16 . 7 . 6 . 17 head = push(head, 17); head = push(head, 7); head = push(head, 6); head = push(head, 16); head = push(head, 15); Console.Write("Original List: "); printList(head); head = deleteNonPrimeNodes(head); Console.Write("\nModified List: "); printList(head); }}// This code is contributed by 29AjayKumar |
Javascript
<script>// javascript implementation to delete all // non-prime nodes from the singly // linked list // Node of the singly linked listclass Node { constructor() { this.data = 0; this.next = null; }} // function to insert a node at the beginning // of the singly Linked List function push(head_ref , new_data) {var new_node = new Node(); new_node.data = new_data; new_node.next = (head_ref); (head_ref) = new_node; return head_ref; } // Function to check if a number is prime function isPrime(n) { // Corner cases if (n <= 1) return false; if (n <= 3) return true; // This is checked so that we can skip // middle five numbers in below loop if (n % 2 == 0 || n % 3 == 0) return false; for (i = 5; i * i <= n; i = i + 6) if (n % i == 0 || n % (i + 2) == 0) return false; return true; } // function to delete all non-prime nodes // from the singly linked list function deleteNonPrimeNodes(head_ref) { // Remove all composite nodes at the beginningvar ptr = head_ref; while (ptr != null && !isPrime(ptr.data)) { var temp = ptr; ptr = ptr.next; } head_ref = ptr; if (ptr == null) return null; // Remove remaining nodesvar curr = ptr.next; while (curr != null) { if (!isPrime(curr.data)) { ptr.next = curr.next; curr = ptr.next; } else { ptr = curr; curr = curr.next; } } return head_ref; } // function to print nodes in a // given singly linked list function printList(head) { while (head != null) { document.write(head.data + " "); head = head.next; } } // Driver code // start with the empty listvar head = null; // create the linked list // 15 . 16 . 7 . 6 . 17 head = push(head, 17); head = push(head, 7); head = push(head, 6); head = push(head, 16); head = push(head, 15); document.write("Original List: "); printList(head); head = deleteNonPrimeNodes(head); document.write("<br/>Modified List: "); printList(head);// This code contributed by aashish1995</script> |
Output
Original List: 15 16 6 7 17 Modified List: 7 17
Complexity Analysis:
- Time Complexity: O(N * sqrt(MAX) ) where N is the total number of nodes in the linked list and MAX is the maximum element in the array.
- Auxiliary Space: O(1).
Recursive Approach:
- Define a function called deleteNonPrimeNodesRecursive that takes a pointer to a node as its argument.
- If the given node is NULL (i.e., the end of the list has been reached), return NULL.
- Recursively call deleteNonPrimeNodesRecursive with the next node in the list as the argument.
- If the next node is NULL, return NULL.
- If the data in the next node is prime, return the next node.
- Otherwise, delete the next node, set the next pointer of the current node to the node after the deleted node, and recursively call deleteNonPrimeNodesRecursive with the current node as the argument.
Below is the implementation of the above approach:
C++
#include <bits/stdc++.h>using namespace std;// Node of the singly linked liststruct Node { int data; Node* next;};// Function to check if a number is primebool isPrime(int n){ // Corner cases if (n <= 1) return false; if (n <= 3) return true; // This is checked so that we can skip // middle five numbers in below loop if (n % 2 == 0 || n % 3 == 0) return false; for (int i = 5; i * i <= n; i = i + 6) if (n % i == 0 || n % (i + 2) == 0) return false; return true;}// Function to delete all non-prime nodes recursivelyNode* deleteNonPrimeNodes(Node* head){ if (head == NULL) { return NULL; } if (isPrime(head->data)) { head->next = deleteNonPrimeNodes(head->next); return head; } return deleteNonPrimeNodes(head->next);}// function to print nodes in a given singly linked listvoid printList(Node* head){ while (head != NULL) { cout << head->data << " "; head = head->next; }}// Function to insert a node at the beginning// of the singly Linked Listvoid 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;}// Driver programint main(){ // start with the empty list Node* head = NULL; // create the linked list // 15 -> 16 -> 7 -> 6 -> 17 push(&head, 17); push(&head, 6); push(&head, 7); push(&head, 16); push(&head, 15); cout << "Original List: "; printList(head); head = deleteNonPrimeNodes(head); cout << "\nModified List: "; printList(head); return 0;} |
Java
class Node { int data; Node next;}public class DeleteNonPrimeNodes { // Function to check if a number is prime static boolean isPrime(int n) { if (n <= 1) return false; if (n <= 3) return true; if (n % 2 == 0 || n % 3 == 0) return false; for (int i = 5; i * i <= n; i = i + 6) if (n % i == 0 || n % (i + 2) == 0) return false; return true; } // Function to delete all non-prime nodes recursively static Node deleteNonPrimeNodes(Node head) { if (head == null) { return null; } if (isPrime(head.data)) { head.next = deleteNonPrimeNodes(head.next); return head; } return deleteNonPrimeNodes(head.next); } // Function to print nodes in a given singly linked list static void printList(Node head) { while (head != null) { System.out.print(head.data + " "); head = head.next; } } // Function to insert a node at the beginning // of the singly Linked List static Node push(Node head, int new_data) { Node new_node = new Node(); new_node.data = new_data; new_node.next = head; head = new_node; return head; } // Driver program public static void main(String[] args) { // start with the empty list Node head = null; // create the linked list // 15 -> 16 -> 7 -> 6 -> 17 head = push(head, 17); head = push(head, 6); head = push(head, 7); head = push(head, 16); head = push(head, 15); System.out.print("Original List: "); printList(head); head = deleteNonPrimeNodes(head); System.out.print("\nModified List: "); printList(head); }}// This code is contributed by akshitaguprzj3 |
Python3
# Node of the singly linked listclass Node: def __init__(self, data): self.data = data self.next = None# Function to check if a number is primedef is_prime(n): # Corner cases if n <= 1: return False if n <= 3: return True # This is checked so that we can skip # middle five numbers in below loop if n % 2 == 0 or n % 3 == 0: return False i = 5 while i * i <= n: if n % i == 0 or n % (i + 2) == 0: return False i += 6 return True# Function to delete all non-prime nodes recursivelydef delete_non_prime_nodes(head): if head is None: return None if is_prime(head.data): head.next = delete_non_prime_nodes(head.next) return head return delete_non_prime_nodes(head.next)# Function to print nodes in a given singly linked listdef print_list(head): while head: print(head.data, end=" ") head = head.next print()# Function to insert a node at the beginning# of the singly Linked Listdef push(head_ref, new_data): new_node = Node(new_data) new_node.next = head_ref head_ref = new_node return head_ref# Driver programif __name__ == "__main__": # start with the empty list head = None # create the linked list # 15 -> 16 -> 7 -> 6 -> 17 head = push(head, 17) head = push(head, 6) head = push(head, 7) head = push(head, 16) head = push(head, 15) print("Original List:", end=" ") print_list(head) head = delete_non_prime_nodes(head) print("Modified List:", end=" ") print_list(head) |
C#
using System;// node of the singly linked listpublic class node { public int data; public node next;}public class linkedList { // Function to check if a number is prime public static bool IsPrime(int n) { // Corner cases if (n <= 1) return false; if (n <= 3) return true; // This is checked so that we can skip // middle five numbers in below loop if (n % 2 == 0 || n % 3 == 0) return false; for (int i = 5; i * i <= n; i = i + 6) { if (n % i == 0 || n % (i + 2) == 0) return false; } return true; } // Function to delete all non-prime nodes recursively public static node DeleteNonPrimeNodes(node head) { if (head == null) { return null; } if (IsPrime(head.data)) { head.next = DeleteNonPrimeNodes(head.next); return head; } return DeleteNonPrimeNodes(head.next); } // Function to print nodes in a given // singly linked list public static void PrintList(node head) { while (head != null) { Console.Write(head.data + " "); head = head.next; } } // Function to insert a node at the beginning // of the singly Linked List public static void Push(ref 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; } // Driver program public static void Main() { // start with the empty list node head = null; // create the linked list // 15 -> 16 -> 7 -> 6 -> 17 Push(ref head, 17); Push(ref head, 6); Push(ref head, 7); Push(ref head, 16); Push(ref head, 15); Console.Write("Original List: "); PrintList(head); head = DeleteNonPrimeNodes(head); Console.Write("\nModified List: "); PrintList(head); }} |
Javascript
class Node { constructor(data) { this.data = data; this.next = null; }}// Function to check if a number is primefunction isPrime(n) { if (n <= 1) return false; if (n <= 3) return true; if (n % 2 === 0 || n % 3 === 0) return false; for (let i = 5; i * i <= n; i += 6) { if (n % i === 0 || n % (i + 2) === 0) return false; } return true;}// Function to delete all non-prime nodes recursivelyfunction deleteNonPrimeNodes(head) { if (head === null) { return null; } if (isPrime(head.data)) { head.next = deleteNonPrimeNodes(head.next); return head; } return deleteNonPrimeNodes(head.next);}// Function to print nodes in a given singly linked listfunction printList(head) { let current = head; while (current !== null) { console.log(current.data + " "); current = current.next; }}// Function to insert a node at the beginning of the singly Linked Listfunction push(head, new_data) { let new_node = new Node(new_data); new_node.next = head; head = new_node; return head;}// Driver programlet head = null;// Create the linked list: 15 -> 16 -> 7 -> 6 -> 17head = push(head, 17);head = push(head, 6);head = push(head, 7);head = push(head, 16);head = push(head, 15);console.log("Original List: ");printList(head);head = deleteNonPrimeNodes(head);console.log("\nModified List: ");printList(head); |
Output
Original List: 15 16 7 6 17 Modified List: 7 17
Time Complexity: O(n), where n is the length of the linked list.
Auxiliary Space: O(n), so the maximum depth of the recursive call stack is equal to the length of the linked list.
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