[LeetCode]Copy List with Random Pointer

public class Solution {
    public RandomListNode copyRandomList(RandomListNode head) {
        if (head == null) {
            return head;
        }
        RandomListNode result = new RandomListNode(head.label);
        //copy next
        RandomListNode p1 = head;
        RandomListNode p2 = result;
        HashMap<RandomListNode, RandomListNode> map = new HashMap<RandomListNode, RandomListNode>();
        map.put(p1, p2);
        while (p1.next != null) {
            p2.next = new RandomListNode(p1.next.label);
            p1 = p1.next;
            p2 = p2.next;
            map.put(p1, p2);
        }
        //copy random
        p1 = head;
        p2 = result;
        while (p1 != null) {
            p2.random = map.get(p1.random);
            p1 = p1.next;
            p2 = p2.next;
        }
        return result;
    }
}

public class Solution {
    public RandomListNode copyRandomList(RandomListNode head) {
        if (head == null) {
            return head;
        }
        RandomListNode p = head;
        while (p != null) {
            RandomListNode copy = new RandomListNode(p.label);
            copy.random = p.random;
            copy.next = p.next;
            p.next = copy;
            p = copy.next;
        }
        p = head.next;
        while (p != null) {
            if (p.random != null)
                p.random = p.random.next;
            if (p.next == null) {
                break;
            }
            p = p.next.next;
        }
        RandomListNode p1 = head;
        RandomListNode p2 = head.next;
        RandomListNode result = p2;
        while (p1 != null && p1.next != null) {
            p1.next = p1.next.next;
            if (p2.next != null)
            p2.next = p2.next.next;
            p1 = p1.next;
            p2 = p2.next;
        }
        return result;
    }
}