package me.ramswaroop.linkedlists;
import me.ramswaroop.common.SingleLinkedList;
import me.ramswaroop.common.SingleLinkedNode;
/**
* Created by IntelliJ IDEA.
*
* @author: ramswaroop
* @date: 6/24/15
* @time: 3:48 PM
*/
public class PairWiseSwap {
/**
* Recursively swaps adjacent nodes of a linked list.
* <p/>
* Example:
* Input: 11->22->33->44->55
* Output: 22->11->44->33->55
*
* @param node
* @return new starting node after swapping adjacent nodes.
*/
public static <E extends Comparable<E>> SingleLinkedNode<E> pairWiseSwap(SingleLinkedNode<E> node) {
if (node == null || node.next == null) return node;
SingleLinkedNode<E> nextNode = node.next, nextOfNextNode = nextNode.next;
nextNode.next = node;
node.next = pairWiseSwap(nextOfNextNode);
return nextNode;
}
public static void main(String a[]) {
SingleLinkedList<Integer> linkedList = new SingleLinkedList<>();
linkedList.add(11);
linkedList.add(22);
linkedList.add(33);
linkedList.add(44);
linkedList.add(55);
linkedList.add(66);
linkedList.add(77);
linkedList.printList();
linkedList.printList(pairWiseSwap(linkedList.head));
}
}