# Linked list Y shape

## Problem

Given two linked lists find out whether they are converged to a single linked list or not, if yes, find there point of convergence.

## Solution

If the linked lists are convergent, then their last node will be same. So we traverse along both the nodes and find the last node of each linked lists. If they are equal then they are convergent.

To find the point of convergence, we first find their corresponding lengths and find their difference. Then we traverse the longer linked list number of nodes equal to the difference. After that if we traverse along the two nodes simultaneously when we find a common node that is the node of convergence.

To find the point of convergence, we first find their corresponding lengths and find their difference. Then we traverse the longer linked list number of nodes equal to the difference. After that if we traverse along the two nodes simultaneously when we find a common node that is the node of convergence.

## Code

public class LinkedListYShape { public static void main(String[] args) { Node head1 = new Node(1); Node middle1 = head1.append(2).append(3).append(4); middle1.append(6).append(7).append(8).append(9); Node head2 = new Node(10); Node middle2 = head2.append(3).append(5).append(6).append(11) .append(24); middle2.next = middle1; findIntersection(head1, head2); } private static void findIntersection(Node head1, Node head2) { int count1 = 0; int count2 = 0; Node ptr1 = head1; Node ptr2 = head2; while (true) { if (ptr1.next == null) break; ptr1 = ptr1.next; count1++; } while (true) { if (ptr2.next == null) break; ptr2 = ptr2.next; count2++; } boolean isMerged = ptr1 == ptr2; if (isMerged) { System.out.println("The linked lists are merged"); Node longer = head1; Node shorter = head2; if (count1 < count2) { longer = head2; shorter = head1; } int diff = Math.abs(count1 - count2); while (diff-- > 0) { longer = longer.next; } while (longer != shorter) { longer = longer.next; shorter = shorter.next; } System.out.println("Common Node = " + longer.value); } else { System.out.println("The linked lists are NOT merged"); } } private static class Node { public Node next; public int value; public Node(int value) { this.value = value; } public Node append(int value) { Node node = new Node(value); next = node; return node; } } }