public RandomListNode copyRandomList(RandomListNode head) {
if (head == null) {
return head;
}
// insert nodes
RandomListNode cur = head;
while (cur != null) {
RandomListNode node = new RandomListNode(cur.label);
node.next = cur.next;
cur.next = node;
cur = cur.next.next;
}
// Copy random List
cur = head;
RandomListNode copy = cur.next;
while (copy != null && cur != null) {
copy.random = cur.random == null ? null : cur.random.next;
cur = cur.next.next;
if (copy.next != null) {
copy = copy.next.next;
}
}
RandomListNode dummy = new RandomListNode(0);
dummy.next = head;
// remove old nodes
copy = dummy;
cur = dummy.next;
while (copy != null && copy.next != null) {
copy.next = copy.next.next;
cur.next = copy.next.next;
copy = copy.next;
cur = cur.next;
}
return dummy.next;
}
