Algorithms—138.Copy List with Random Pointer

思路：很简单的一题，next当作主线递归赋值，random作为支线附上即可。

/**
* 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) {
RandomListNode answer=null;
if (head!=null) {
answer=new RandomListNode(head.label);
}else {
return null;
}
if (head.random!=null) {
answer.random=new RandomListNode(head.random.label);
}
answer.next=copyRandomList(head.next);
return answer;
}
}

耗时：356ms，中游