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;
}