LinkedList - Deep copy

CopyRandomList.java

package com.interviewbytes.linkedlists;

import java.util.HashMap;
import java.util.Map;

public class CopyRandomList {

    public RandomListNode copyRandomList(RandomListNode head) {

        Map<RandomListNode, RandomListNode> mapping = new HashMap<>();

        RandomListNode current = head;

        while (current != null) {
            if (!mapping.containsKey(current)) {
                mapping.put(current, new RandomListNode(current.label));
            }
            current = current.next;
        }

        RandomListNode sentinel = new RandomListNode(0);
        current = sentinel;

        while (head != null) {
            current.next = mapping.get(head);
            current = current.next;
            current.next = mapping.get(head.next);
            current.random = mapping.get(head.random);

            head = head.next;
        }

        return sentinel.next;
    }
}

RandomListNode.java

package com.interviewbytes.linkedlists;

public class RandomListNode {

    int label;
    RandomListNode next, random;

    RandomListNode(int x) {
        this.label = x;
    }
}