SublistSearch.java

// Path: C\Searching\sublist_search.c
// C program to check whether the first list is present in 2nd list or not, when two linked lists are given.
// Time-Complexity: O(M*N), where M is the number of nodes in the second list and N in the first.
// Auxiliary-Space: O(1). 

import java.util.Scanner;

// Main class
public class SublistSearch {
 // Class representing a node in the linked list
 static class Node {
 int data;
 Node next;
 
 Node(int data) {
 this.data = data;
 this.next = null;
 }
 }
 
 // Class representing the linked list
 static class SingleLinkedList {
 Node head;
 
 // Function to insert a node at the end of the linked list
 void insertAtEnd(int data) {
 Node newNode = new Node(data);
 
 // If the list is empty, make the new node the head
 if (head == null) {
 head = newNode;
 return;
 }
 
 // Traverse to the last node
 Node temp = head;
 while (temp.next != null) {
 temp = temp.next;
 }
 
 // Insert the new node at the end
 temp.next = newNode;
 }
 
 // Function to display the linked list
 void displayList() {
 Node temp = head;
 if (temp == null)
 System.out.print("NULL");
 while (temp != null) {
 System.out.print(temp.data + " ");
 temp = temp.next;
 }
 System.out.println();
 }
 
 // Returns true if first list is present in second list else false
 boolean isSublist(SingleLinkedList list1, SingleLinkedList list2) {
 // If list1 and list2 are null (Empty), list1 is sublist of list2
 if (list1.head == null && list2.head == null) {
 return true;
 }
 
 // Else, if list1 is null and list2 is not, return false
 if (list1.head == null) {
 return false;
 }
 
 // current1 is to traverse in list1 and current2 in list2
 Node current1 = list1.head;
 Node current2 = list2.head;
 
 // Traverse the second list by picking nodes one by one
 while (list2.head != null) {
 // Initialize current2 pointer with the current node of the list2
 current2 = list2.head;
 
 // Start matching the first list with the second list
 while (current1 != null) {
 // If the second list becomes empty and the first list does not, return false
 if (current2 == null) {
 return false;
 }
 
 // If the data part is the same, go to the next nodes of both lists
 else if (current1.data == current2.data) {
 current1 = current1.next;
 current2 = current2.next;
 }
 
 // If they are not equal, break the loop
 else {
 break;
 }
 }
 
 // Returns True, If list1 is traversed completely (till the end)
 // Indicating that list1 is found
 if (current1 == null) {
 return true;
 }
 
 // Initialize current1 pointer with first again
 current1 = list1.head;
 
 // Move to the next node of the second list
 list2.head = list2.head.next;
 }
 
 return false;
 }
 }

 public static void main(String[] args) {
 // Create the first linked list
 SingleLinkedList list1 = new SingleLinkedList();

 Scanner scanner = new Scanner(System.in);

 // Size of list1
 System.out.print("No of Nodes in the first list: ");
 int N = scanner.nextInt();

 for (int i = 0; i < N; i++) {
 System.out.print("data " + (i + 1) + ": ");
 int data = scanner.nextInt();

 list1.insertAtEnd(data);
 }
 System.out.println();

 // Create the second linked list
 SingleLinkedList list2 = new SingleLinkedList();

 // Size of list2
 System.out.print("No of Nodes in the second list: ");
 int M = scanner.nextInt();

 for (int i = 0; i < M; i++) {
 System.out.print("data " + (i + 1) + ": ");
 int data = scanner.nextInt();

 list2.insertAtEnd(data);
 }
 System.out.println();

 // Display the first linked list
 System.out.print("List 1: ");
 list1.displayList();

 // Display the second linked list
 System.out.print("List 2: ");
 list2.displayList();
 System.out.println();

 // Check if the first list is a sublist of the second list
 boolean result = list1.isSublist(list1, list2);
 System.out.print("Is the first list a sublist of the second list? ");

 if (result) {
 System.out.println("True\n");
 } else {
 System.out.println("False\n");
 }

 scanner.close();
 }
}