/*** Definition for singly-linked list with a random pointer.* class RandomListNode {*     int label;*     RandomListNode next, random;*     RandomListNode(int x) { this.label = x; }* };*/
public class Solution {public RandomListNode copyRandomList(RandomListNode head) {if (head == null) {return head;}Map<RandomListNode, RandomListNode> map = new HashMap<RandomListNode, RandomListNode>();RandomListNode copyHead = new RandomListNode(head.label);RandomListNode head1 = head;RandomListNode returnHead = copyHead;map.put(head1, copyHead);while(head1.next != null) {copyHead.next = new RandomListNode(head1.next.label);map.put(head1.next, copyHead.next);copyHead = copyHead.next;head1 = head1.next;}copyHead = returnHead;head1 = head;while(copyHead != null) {copyHead.random = map.get(head1.random);copyHead = copyHead.next;head1 = head1.next;}return returnHead;}
}

/*** Definition for singly-linked list with a random pointer.* class RandomListNode {*     int label;*     RandomListNode next, random;*     RandomListNode(int x) { this.label = x; }* };*/
public class Solution {public RandomListNode copyRandomList(RandomListNode head) {if (head == null) {return head;}RandomListNode returnHead = head;//在原链表的每个节点后都插入一个新节点while(head != null) {RandomListNode newNode = new RandomListNode(head.label);newNode.next = head.next;head.next = newNode;head = head.next.next;}//将每个复制的节点的random指向它前一个节点的random的nexthead = returnHead;while(head != null) {if(head.random != null) {head.next.random = head.random.next;}head = head.next.next;}//抽出每个复制的节点，返回head = returnHead;returnHead = returnHead.next;while(head != null) {RandomListNode newNode = head.next;head.next = head.next.next;//这个边界条件一定要注意，否则原链表只有一个节点的时候会越界if(newNode.next != null) {newNode.next = newNode.next.next;}head = head.next;}return returnHead;}
}