[LeetCode]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.

利用hashMap存储，原始的node作为key，new的node作为value，这样就建立了新旧链表的以一一对应关系；

/** * 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 {Map<RandomListNode,RandomListNode> map = new HashMap<>();public RandomListNode copyRandomList(RandomListNode head) {RandomListNode scan = head;RandomListNode res = new RandomListNode(0);RandomListNode dummy = res;while(scan!=null){RandomListNode rln = new RandomListNode(scan.label);map.put(scan, rln);dummy.next = rln;scan = scan.next;dummy = dummy.next;}RandomListNode scan2 = head;RandomListNode dummy2 = res.next;while(scan2!=null){if(scan2.random==null){dummy2.random = null;}else{dummy2.random = map.get(scan2.random);}dummy2 = dummy2.next;scan2 = scan2.next;}return res.next;}}