Java for LeetCode 138 Copy List with Random Pointer

A linked list is given such that each node contains an additional random pointer which could point to any node in the list or null.

Return a deep copy of the list.

解题思路：

我们在Java for LeetCode 133 Clone Graph题中做过图的复制，本题和图的复制十分类似，JAVA实现如下：

    public RandomListNode copyRandomList(RandomListNode head) {
		if (head == null)
			return null;
		HashMap<RandomListNode, RandomListNode> map = new HashMap<RandomListNode, RandomListNode>();
		RandomListNode node = new RandomListNode(head.label);
		RandomListNode headTemp = head, nodeTemp = node;
		map.put(head, node);
		while (headTemp.next != null) {
			nodeTemp.next = new RandomListNode(headTemp.next.label);
			map.put(headTemp.next, nodeTemp.next);
			headTemp = headTemp.next;
			nodeTemp = nodeTemp.next;
		}
		headTemp = head;
		nodeTemp = node;
		while (headTemp!= null) {
			if(map.containsKey(headTemp.random))
				nodeTemp.random=map.get(headTemp.random);
			headTemp = headTemp.next;
			nodeTemp = nodeTemp.next;
		}
		return node;
    }