find the triplet sum in java linked list

// Java program to find a triplet from three linked lists with 
// sum equal to a given number 
class LinkedList 
{ 
    Node head;  // head of list 
  
    /* Linked list Node*/
    class Node 
    { 
        int data; 
        Node next; 
        Node(int d) {data = d; next = null; } 
    } 
  
    /* A function to chech if there are three elements in a, b 
      and c whose sum is equal to givenNumber.  The function 
      assumes that the list b is sorted in ascending order and 
      c is sorted in descending order. */
   boolean isSumSorted(LinkedList la, LinkedList lb, LinkedList lc, 
                       int givenNumber) 
   { 
      Node a = la.head; 
  
      // Traverse all nodes of la 
      while (a != null) 
      { 
          Node b = lb.head; 
          Node c = lc.head; 
  
          // for every node in la pick 2 nodes from lb and lc 
          while (b != null && c!=null) 
          { 
              int sum = a.data + b.data + c.data; 
              if (sum == givenNumber) 
              { 
                 System.out.println("Triplet found " + a.data + 
                                     " " + b.data + " " + c.data); 
                 return true; 
              } 
  
              // If sum is smaller then look for greater value of b 
              else if (sum < givenNumber) 
                b = b.next; 
  
              else
                c = c.next; 
          } 
          a = a.next; 
      } 
      System.out.println("No Triplet found"); 
      return false; 
   } 
  
  
    /*  Given a reference (pointer to pointer) to the head 
       of a list and an int, push a new node on the front 
       of the list. */
    void push(int new_data) 
    { 
        /* 1 & 2: Allocate the Node & 
                  Put in the data*/
        Node new_node = new Node(new_data); 
  
        /* 3. Make next of new Node as head */
        new_node.next = head; 
  
        /* 4. Move the head to point to new Node */
        head = new_node; 
    } 
  
     /* Driver program to test above functions */
    public static void main(String args[]) 
    { 
        LinkedList llist1 = new LinkedList(); 
        LinkedList llist2 = new LinkedList(); 
        LinkedList llist3 = new LinkedList(); 
  
        /* Create Linked List llist1 100->15->5->20 */
        llist1.push(20); 
        llist1.push(5); 
        llist1.push(15); 
        llist1.push(100); 
  
        /*create a sorted linked list 'b' 2->4->9->10 */
        llist2.push(10); 
        llist2.push(9); 
        llist2.push(4); 
        llist2.push(2); 
  
        /*create another sorted linked list 'c' 8->4->2->1 */
        llist3.push(1); 
        llist3.push(2); 
        llist3.push(4); 
        llist3.push(8); 
  
        int givenNumber = 25; 
        llist1.isSumSorted(llist1,llist2,llist3,givenNumber); 
    } 
} /* This code is contributed by Rajat Mishra */