拷贝RandomList

/**
 * 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) {
        // Note: The Solution object is instantiated only once and is reused by each test case.
        //应该是在每个节点后拷贝一份自己的节点，然后将自己的random赋值个自己的next节点
        RandomListNode newHead = null;
        if(head != null) {
            RandomListNode p = head;
            while(p != null) {
                RandomListNode copyNode = new RandomListNode(p.label);
                copyNode.next = p.next;
                p.next = copyNode;
                p = copyNode.next;
            }
            p = head;
            while(p!= null) {
                if(p.random != null) {
                    p.next.random = p.random.next;
                }//p.random = null = =
                p = p.next.next;
            }
            p = head;
            newHead = p.next;
            RandomListNode newPreP = null;
            while (p!=null) {
                if(newPreP == null) {
                    newPreP = p.next;
                    
                }
                else {
                    newPreP.next = p.next;
                    newPreP = p.next;
                }
                    p.next = newPreP.next;
                    //p.random = null;
                    p = p.next;
            }
            
        }
        
        return newHead;
    }
}