leetcode copy List with Random

該算法更爲巧妙，不用保存原始鏈表的映射關係，構建新節點時，指針作以下變化，即把新節點插入到相應的舊節點後面：

一、構建新節點random指針：new1->random = old1->random->next, new2-random = NULL, new3-random = NULL, new4->random = old4->random->next

二、恢復原始鏈表以及構建新鏈表：例如old1->next = old1->next->next,  new1->next = new1->next->next

本人額原算法超時：
public class CopyListRandom {

    
    private static class RandomListNode{
        int lable;
        RandomListNode next=null,random=null;
        RandomListNode(int x){
            this.lable=x;
        }
    }
    
    public RandomListNode copyRandomList(RandomListNode head){
        if(head==null)
            return null;
        RandomListNode p=head;
        RandomListNode q=deepCopy(p),r=q;
        System.out.println("p"+p.lable);
        p=head;
        System.out.println("ph:"+p.lable);
        while(p!=null){
            RandomListNode tmp=head,s=q;
            while(p.random!=tmp){
                tmp=tmp.next;
                s=s.next;
            }
            r.random=s;
            r=r.next;
            p=p.next;
        }
        return q;
    }
    public RandomListNode deepCopy(RandomListNode p){
        RandomListNode another=null;
        if(p!=null){
            another=new RandomListNode(p.lable);
            another.next=deepCopy(p.next);
        }
        return another;
    }
    public static void main(String[] args){
        RandomListNode head=new RandomListNode(1);
        RandomListNode head1=new RandomListNode(2);
        RandomListNode head2=new RandomListNode(3);
        RandomListNode head3=new RandomListNode(4);
        RandomListNode head4=new RandomListNode(5);
        RandomListNode head5=new RandomListNode(6);
        head.next=head1;
        head1.next=head2;
        head2.next=head3;
        head3.next=head4;
        head4.next=head5;
        head5.next=null;
        head.random=head2;
        head1.random=head3;
        head2.random=head4;
        head3.random=head5;
        head4.random=head;
        head5.random=head1;
        RandomListNode tmp=head;
        while(tmp!=null){
            System.out.println(tmp+"  "+tmp.lable+" random:"+tmp.random.lable);
            tmp=tmp.next;
        }
        CopyListRandom copy=new CopyListRandom();
        RandomListNode tmp2=copy.copyRandomList(head);
        while(tmp2!=null){
            System.out.println(tmp2+"  "+tmp2.lable+"  random:"+tmp2.random.lable);
            tmp2=tmp2.next;
        }
    }
}

上述方法的代碼私下：

package com.demo.acm;

public class CopyListRandom {

    
    private static class RandomListNode{
        int label;
        RandomListNode next=null,random=null;
        RandomListNode(int x){
            this.label=x;
        }
    }
    
    public RandomListNode copyRandomList(RandomListNode head){
        if(head==null)
            return null;
        RandomListNode p=head,q=head;
        p=deepCopy(p);//指針複製
        //兩個鏈表合併
        while(q!=null){
            RandomListNode tmp1=q.next,tmp2=p.next;
            q.next=p;
            p.next=tmp1;
            p=tmp2;
            q=tmp1;
        }
        //將合併鏈表的隨機指針整合
        q=head;
        p=head.next;
        while(q!=null){
            if(q.random!=null){
                p.random=q.random.next;
            }else{
                p.random=null;
            }
            if(q.next.next!=null){
                q=q.next.next;
            }else{
                break;
            }
            if(p.next!=null){
                p=p.next.next;
            }else{
                break;
            }    
        }
        //分拆成兩個鏈表
        q=head;
        p=head.next;
        RandomListNode tmp=p;
        while(q!=null){
            if(q.next.next!=null){
                q.next=q.next.next;
                q=q.next;
            }else{
                q.next=null;
                q=q.next;
            }
            if(p.next!=null){
                p.next=p.next.next;
                p=p.next;
            }
            else{
                p.next=null;
                p=p.next;
            }
        }
        return tmp;
    }
    public RandomListNode deepCopy(RandomListNode p){
        RandomListNode another=null;
        if(p!=null){
            another=new RandomListNode(p.label);
            another.next=deepCopy(p.next);
        }
        return another;
    }
    public static void main(String[] args){
        RandomListNode head=new RandomListNode(1);
        RandomListNode head1=new RandomListNode(2);
        RandomListNode head2=new RandomListNode(3);
        RandomListNode head3=new RandomListNode(4);
        head.next=head1;
        head1.next=head2;
        head1.random=head2;
        head2.next=head3;
        head3.next=null;
        CopyListRandom copy=new CopyListRandom();
        RandomListNode tmp=copy.copyRandomList(head);
        while(tmp!=null){
            System.out.println(tmp.label);
            if(tmp.random!=null)
                System.out.println("random:"+tmp.random.label);
            tmp=tmp.next;
        }
    }
}