Linked List: Sum two Linked Lists

Problem Statement:
      Given two linked lists, represented as numbers , represent the resultant sum of two linked linked list as a linked list.

Fig: Given Lists and resultant list

     Solution :

Steps Involved: 

1. Generate the number from both the linked list using addition(Node , int) method.
2. Add the numbers generated by the linked list to calculate the sum.
3. Use the generated sum to create a linked list in which nodes are appended in the beggining of the list.

Full Source Code: LINK

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/**  * Procedure to calulate resultant list  * @param head1: head of 1st list  * @param head2: head of 2st list  * @return  */ public Node addLists(Node head1 , Node head2) {  int sum1 = addition(head1,0); //sum of 1st list  int sum2 = addition(head2,0); //sum of 2nd list  return createList(sum1 + sum2); }   /**  * Adds all the elements in the list  * @return added sum  */ public int addition(Node head ,int sum){  if(head==null)     return sum;     sum = sum*10 + head.data;  return  addition(head.next , sum) ; }   /**  * Creating list of the total sum Obtained  * @param totSum is sum of the two list obtained  * @return head of the new list created  */ public Node createList(int totSum){  Node head=null;     while(totSum > 0){   int val =totSum%10 ;   totSum = totSum/10;   head=insert(val,head);  }     return head; }   /**  * Inserts node at the beggining  * @return head of the list  */ public Node insert(int val , Node head){  Node node= new Node(val);     if(head==null)   head=node;  else  {   node.next = head;   head=node;  }  return head; }   /**  * Prints the new list created  * @param head  */ public void displayList(Node head) {  Node tempNode;  tempNode=head;  while(tempNode!=null)  {   System.out.print(tempNode.data+"-->");   tempNode=tempNode.next;  }  System.out.print("null");  System.out.println(); }

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Happy Coding !! :)