LeetCode: Copy List with Random Pointer

题目很简单，直接贴答案：

RandomListNode *copyRandomList(RandomListNode *head) {
	if (!head){
		return NULL;
	}
	RandomListNode* cur = head;
	RandomListNode* result = new RandomListNode(head->label);
	RandomListNode* resCur = result;
	unordered_map<RandomListNode*, RandomListNode*> nodes;
	nodes.insert(make_pair(cur, resCur));
	nodes.insert(make_pair((RandomListNode*)NULL, (RandomListNode*)NULL));
	while (cur->next){
		auto next = cur->next;
		auto random = cur->random;
		auto it = nodes.find(next);
		if (it == nodes.end()){
			RandomListNode* tmp = new RandomListNode(next->label);
			nodes.insert(make_pair(next, tmp));
			resCur->next = tmp;
		}
		else{
			resCur->next = it->second;
		}
		it = nodes.find(random);
		if (it == nodes.end()){
			RandomListNode* tmp = new RandomListNode(random->label);
			nodes.insert(make_pair(random, tmp));
			resCur->random = tmp;
		}
		else{
			resCur->random = it->second;
		}
		cur = cur->next;
		resCur = resCur->next;
	}

	auto it = nodes.find(cur->random);
	resCur->random = it->second;
	resCur->next = NULL;
	return result;
}