intersectionoflinkedlist.txt

#include <bits/stdc++.h> 
/****************************************************************
 
    Following is the class structure of the Node class:

        class Node
        {
        public:
	        int data;
	        Node *next;
	        Node(int data)
	        {
		        this->data = data;
		        this->next = NULL;
	        }
        };

*****************************************************************/

int length(Node* head){

   int count = 0;

   

   while(head!=NULL){

       count++;

       head = head->next;

   }

   return count;

}

 

int findIntersection(Node *firstHead, Node *secondHead){

   

   if(firstHead == NULL || secondHead == NULL) return -1;

   

   Node* temp1 = firstHead;

   Node* temp2 = secondHead;

   

   int l1 = length(temp1);

   int l2 = length(temp2);

   

   if(l1-l2 < 0){

       int diff = l2-l1;

       while(diff--) temp2 = temp2->next;

   }

   else{

       int diff = l1-l2;

       while(diff--) temp1 = temp1->next;

   }

   

   while(temp1!=temp2 && temp1->next!=NULL && temp2->next!=NULL){

       

       temp1 = temp1->next;

       temp2 = temp2->next;

       

   }

   

   if(temp1 == temp2) return temp1->data;

   else return -1;

}