java-basics/java-programs/LinkedListCheckCyclic.java at master · CodeForHunger/java-basics · GitHub

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package misc;

import java.util.HashSet;

/**

* Algorithm:-

* 1) Use two pointers fast and slow

* 2) Move fast two nodes and slow one node in each iteration

* 3) If fast and slow meet then linked list contains cycle

* 4) If fast points to null or fast.next points to null then linked list is not cyclic

public class LinkedListCheckCyclic {

static Node head; // head of list

/* Linked list Node*/

static class Node {

int data;

Node next;

Node(int d) {data = d; next = null; }

}

/* Inserts a new Node at front of the list. */

static public void push(int new_data) {

Node new_node = new Node(new_data);

new_node.next = head;

head = new_node;

}

static boolean isCyclic() {

Node fast = head;

Node slow = head;

while(fast != null && fast.next != null) {

fast = fast.next.next;

slow = slow.next;

if(fast == slow) {

return true;

}

return false;

}

public static void main(String[] args) {

LinkedListCheckCyclic linkedList = new LinkedListCheckCyclic();

linkedList.push(101);

linkedList.push(201);

linkedList.push(301);

linkedList.push(401);

/*Create loop for testing */

// linkedList.head.next.next.next.next = linkedList.head;

if (isCyclic())

System.out.println("Linked List is Cyclic !!!");

else

System.out.println("Linked List is Not Cyclic !");

}

java-basics/java-programs/LinkedListCheckCyclic.java at master · CodeForHunger/java-basics · GitHub

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