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.

题目意思是复制一个节点带有随机指针的链表。

方法是先把链表放入LIST内，然后遍历list为每个节点添加随机指针。

/**
 * 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 null;
        }
        ArrayList<RandomListNode> oldList=new ArrayList<>();
        ArrayList<RandomListNode> newList=new ArrayList<>();
        int indexRandom;
        RandomListNode tempNode=head;
        while (tempNode!=null) {
            oldList.add(tempNode);
            newList.add(new RandomListNode(tempNode.label));
            tempNode=tempNode.next;
        }
        for (int i = 0; i < oldList.size(); i++) {
            if (i<oldList.size()-1) {
                newList.get(i).next=newList.get(i+1);
            }
            indexRandom=oldList.indexOf(oldList.get(i).random);
            if (indexRandom>=0) {
                newList.get(i).random=newList.get(indexRandom);
            }
        }
        
        return newList.get(0);
    }
}