Intersection point two linked lists

#1

Only one test case is giving me run-error. Kindly help me with the problem.

#2

@jeevanshu,
can you please share your code

#3

import java.util.*;
public class Main {

public static void main(String args[]) {
	Scanner sc=new Scanner(System.in);
	int size=sc.nextInt();
	LinkedList l1=new LinkedList();
	for(int i=0;i<size;i++){
		l1.addLast(sc.nextInt());
	}
	int size2=sc.nextInt();
	LinkedList l2=new LinkedList();
	for(int i=0;i<size2;i++){
		l2.addLast(sc.nextInt());
	}
	System.out.println(l1.findIntersection(l1.head,l2.head));
}
private static class LinkedList {
private class Node {
	int data;
	Node next;
	public Node(int data) {
		 this.data=data;
		 this.next=null;
	}
	
	
}
private Node head;
private Node tail;
private int size;
//O(N)
public void display(){
	Node temp=this.head;
	while(temp!=null){
		System.out.print(temp.data+" ");
		temp=temp.next;
	}
	System.out.println();
}
//O(N)
public void addLast(int data){
	 Node newNode=new Node(data);

	 this.size++;
	if(head==null){
		head=newNode;
		tail=newNode;
		return;
	}
	 tail.next=newNode;
	 this.tail=newNode;
}
public int findIntersection(Node l1, Node l2){
	Node l1Head=l1;
	Node l2Head=l2;
	int count1=0,count2=0;
	while(l1Head!=null){
		l1Head=l1Head.next;
		count1++;
	}
	while(l2Head!=null){
		l2Head=l2Head.next;
		count2++;
	}
	int d=count1-count2;
	l1Head=l1;
	l2Head=l2;
	int count=0;
	while(count!=d){
		l1Head=l1Head.next;
		count++;
	}
	while(l1Head!=null && l2Head!=null){
		if(l1Head.data==l2Head.data){
			return l1Head.data;
		}
		l1Head=l1Head.next;
		l2Head=l2Head.next;
	}
	return -1;
}
public int size(){
	return this.size;
}
//O(1)
public void addFirst(int data){
	Node newNode=new Node(data);
	this.size++;
	if(head==null){
		head=newNode;
		tail=newNode;
		return;
	}
	newNode.next=head;
	head=newNode;
}
//O(N)
private Node getNodeAt(int index){
	int count=0;
	if(this.size==0){
		return null;
	}
	Node temp=head;
	while(temp!=null){
		if(count==index){
			return temp;
		}else{
			count++;
		}
		temp=temp.next;
	}
	return null;
}
//O(1)
public int getFirst(){
	if(head==null){
		return -1;
	}
	return this.head.data;
}
//O(1)
public int getLast(){
	if(tail==null){
		return -1;
	}
	return this.tail.data;
}
//O(N)
public int getAt(int index){
	if(size==0){
		return -1;
	}else if(index<0 || index>=this.size){
		return -1;
	}
	
	int count=0;
	Node temp=head;
	while(temp!=null){
		if(count==index){
			return temp.data;
		}else{
			count++;
		}
		temp=temp.next;
	}
	return -1;
}
//O(1)
public int removeFirst(){
	if(head==null){
		return -1;
	}
	int rv=head.data;
	if(this.size==1){
		this.size=0;
		this.head=null;
		this.tail=null;
	}
	head=head.next;
	this.size--;
	return rv;
}

//O(N)
public int removeLast(){
	if(tail==null){
		return -1;
	}
	if(size==1){
		this.size=0;
		this.head=null;
		this.tail=null;
	}
	int rv=tail.data;
	Node temp=getNodeAt(size-2);
	tail=temp;
	tail.next=null;
	this.size--;
	return rv;
}

//O(N)
public int removeAt(int index){
	if(size==0){
		return -1;
	}else if(index<0 || index>=size){
		return -1;
	}else if(index==0){
		return removeFirst();
	}else if(index==size-1){
		return removeLast();
	}else{
		Node node=getNodeAt(index-1);
		Node nextNode=node.next;
		Node nextOfNextNode=nextNode.next;
		node.next=nextOfNextNode;
		this.size--;
		return nextNode.data;
	}
}
//reverse data
public void reverseList(){
	if(size==0){
		return;
	}
	int left=0;
	int right=this.size-1;
	while(left<right){
		Node leftNode=getNodeAt(left);
		Node rightNode=getNodeAt(right);
		int temp=leftNode.data;
		leftNode.data=rightNode.data;
		rightNode.data=temp;
		left++;
		right--;
	}
}

public void reversePointers(){
	Node prev=this.head;
	Node temp=prev.next;
	while(temp!=null){
		Node next=temp.next;
		temp.next=prev;
		prev=temp;
		temp=next;
	}
	Node t=this.head;
	this.head=this.tail; 
	this.tail= t;
	this.tail.next=null;
}

public int midNode(){
	Node slow=this.head;
	Node fast=slow.next;
	
	while(fast.next!=null && fast.next.next!=null){
		slow=slow.next;
		fast=fast.next.next;
	}
	
	return slow.data;
}

}

}

#4

@jeevanshu,
your code will give error if the no. of elements in second array> no. of elements in first array

#5

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