solution.java

import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;

public class Solution {

    static class SinglyLinkedListNode {
        public int data;
        public SinglyLinkedListNode next;

        public SinglyLinkedListNode(int nodeData) {
            this.data = nodeData;
            this.next = null;
        }
    }

    static class SinglyLinkedList {
        public SinglyLinkedListNode head;
        public SinglyLinkedListNode tail;

        public SinglyLinkedList() {
            this.head = null;
            this.tail = null;
        }

        public void insertNode(int nodeData) {
            SinglyLinkedListNode node = new SinglyLinkedListNode(nodeData);

            if (this.head == null) {
                this.head = node;
            } else {
                this.tail.next = node;
            }

            this.tail = node;
        }
    }

    public static void printSinglyLinkedList(SinglyLinkedListNode node, String sep, BufferedWriter bufferedWriter) throws IOException {
        while (node != null) {
            bufferedWriter.write(String.valueOf(node.data));

            node = node.next;

            if (node != null) {
                bufferedWriter.write(sep);
            }
        }
    }

    //In this method we will use two pointer approach 
    //If both the pointers collide it signifies the Linked List has a cycle
    static boolean hasCycle(SinglyLinkedListNode head) {
        //If head is null no cycle exists
	if(head == null) {
            return false;
        }
        SinglyLinkedListNode fastPtr = head;	//Moves two steps at a time
	SinglyLinkedListNode slowPtr = head;	//Moves one step at a time
        
	while(fastPtr != null && fastPtr.next != null) {
            slowPtr = slowPtr.next;
            fastPtr = fastPtr.next.next;
	    //Slow and fast collided hence return true
            if(slowPtr == fastPtr) {
                return true;
            }
        }
	//If the two pointer don't collide return false
        return false;
    }

    private static final Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) throws IOException {
        BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

        int tests = scanner.nextInt();
        scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");

        for (int testsItr = 0; testsItr < tests; testsItr++) {
            int index = scanner.nextInt();
            scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");

            SinglyLinkedList llist = new SinglyLinkedList();

            int llistCount = scanner.nextInt();
            scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");

            for (int i = 0; i < llistCount; i++) {
                int llistItem = scanner.nextInt();
                scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");

                llist.insertNode(llistItem);
            }
          
          	SinglyLinkedListNode extra = new SinglyLinkedListNode(-1);
            SinglyLinkedListNode temp = llist.head;

            for (int i = 0; i < llistCount; i++) {
                if (i == index) {
                    extra = temp;
                }

                if (i != llistCount-1) {
                    temp = temp.next;
                }
            }
      
      		temp.next = extra;

            boolean result = hasCycle(llist.head);

            bufferedWriter.write(String.valueOf(result ? 1 : 0));
            bufferedWriter.newLine();
        }

        bufferedWriter.close();

        scanner.close();
    }
}