package me.ramswaroop.linkedlists;
import me.ramswaroop.common.SingleLinkedList;
import me.ramswaroop.common.SingleLinkedNode;
/**
* Created by IntelliJ IDEA.
*
* @author: ramswaroop
* @date: 6/18/15
* @time: 10:34 PM
*/
public class IntersectionPointOfTwoLists {
/**
* Returns the node at which {@param list1} and {@param list2} intersect.
*
* @param list1
* @param list2
* @param <E>
* @return
*/
public static <E extends Comparable<E>> SingleLinkedNode<E> getIntersectionNode(SingleLinkedList<E> list1,
SingleLinkedList<E> list2) {
SingleLinkedNode<E> curr1, curr2;
int diffLength = Math.abs(list1.size - list2.size);
// forward the pointer in the longer list by their diff. in length
if (list1.size > list2.size) {
curr1 = list1.head;
curr2 = list2.head;
} else {
curr1 = list2.head;
curr2 = list1.head;
}
while (diffLength > 0) {
curr1 = curr1.next;
diffLength--;
}
// now compare both lists node by node
while (curr1 != null) {
if (curr1 == curr2) return curr1;
curr1 = curr1.next;
curr2 = curr2.next;
}
// lists do not intersect
return null;
}
public static void main(String a[]) {
SingleLinkedList<Integer> linkedList1 = new SingleLinkedList<>();
linkedList1.add(00);
linkedList1.add(11);
linkedList1.add(22);
linkedList1.add(33);
linkedList1.add(44);
linkedList1.add(55);
linkedList1.add(66);
linkedList1.add(77);
linkedList1.add(88);
SingleLinkedList<Integer> linkedList2 = new SingleLinkedList<>();
linkedList2.add(56);
linkedList2.add(78);
linkedList2.add(45);
linkedList2.add(23);
linkedList2.getNode(3).next = linkedList1.getNode(5); // join 2 lists at some point
linkedList2.size = 8; // IMP: update size after joining
System.out.println(getIntersectionNode(linkedList1, linkedList2) != null ?
getIntersectionNode(linkedList1, linkedList2).item : "List don't intersect!");
}
}