Copy List with Random Pointer

/**
 * Definition for singly-linked list with a random pointer.
 * class RandomListNode {
 *     int label;
 *     RandomListNode next, random;
 *     RandomListNode(int x) { this.label = x; }
 * };
 */
public class Solution {
    /**
     * @param head: The head of linked list with a random pointer.
     * @return: A new head of a deep copy of the list.
     */
    public RandomListNode copyRandomList(RandomListNode head) {
		Map<Integer, RandomListNode> map = new HashMap<Integer, RandomListNode>();

		RandomListNode chead = createList(map, head);

		RandomListNode p = chead;
		while (head != null) {
			if (head.random != null)
				p.random = map.get(head.random.label);
			head = head.next;
			p = p.next;
		}
		return chead;
	}

	RandomListNode createList(Map<Integer, RandomListNode> map, RandomListNode node) {
		if (node == null)
			return null;

		RandomListNode cnext = null;
		if (node.next != null)
			cnext = createList(map, node.next);

		RandomListNode cnode = new RandomListNode(node.label);
		cnode.next = cnext;
		map.put(node.label, cnode);
		return cnode;
	}
}

/**
 * Definition for singly-linked list with a random pointer.
 * class RandomListNode {
 *     int label;
 *     RandomListNode next, random;
 *     RandomListNode(int x) { this.label = x; }
 * };
 */
public class Solution {
    /**
     * @param head: The head of linked list with a random pointer.
     * @return: A new head of a deep copy of the list.
     */
    public RandomListNode copyRandomList(RandomListNode head) {
		if (head == null)
			return null;

		RandomListNode p = head;
		while (p != null) {
			RandomListNode np = new RandomListNode(p.label);
			np.next = p.next;
			p.next = np;
			p = np.next;
		}

		p = head;
		while (p != null) {
			if (p.random != null)
				p.next.random = p.random.next;
			p = p.next.next;
		}

		p = head.next;
		while (p != null) {
			if (p.next != null)
				p.next = p.next.next;
			p = p.next;
		}

		return head.next;
	}
}