剑指offer35--复杂链表的复制——java/C++实现

题目描述

输入一个复杂链表（每个节点中有节点值，以及两个指针，一个指向下一个节点，另一个特殊指针指向任意一个节点），返回结果为复制后复杂链表的head。（注意，输出结果中请不要返回参数中的节点引用，否则判题程序会直接返回空）

思路：

哈希表法

1. 先复制一个链表，同时用哈希表存储所有指针
2. 然后再遍历链表，利用哈希表复制所有指针

/*
struct RandomListNode {
    int label;
    struct RandomListNode *next, *random;
    RandomListNode(int x) :
            label(x), next(NULL), random(NULL) {
    }
};
*/

class Solution {
public:
    RandomListNode* Clone(RandomListNode* pHead)
    {
        if (pHead == nullptr)
        {
           return nullptr;
        }
         std::unordered_map<RandomListNode*, RandomListNode*> hash_map;
         RandomListNode* ptmp=pHead;
         RandomListNode* CopyHead=new RandomListNode(pHead->label);
         RandomListNode* p1=CopyHead;
         hash_map[pHead]=CopyHead;
         pHead=pHead->next; 
         for (RandomListNode* p = pHead; p != nullptr; p = p->next)
         {
             RandomListNode* tmp=new RandomListNode(p->label);
             p1->next=tmp;
             p1=p1->next;
             hash_map[p]=p1;
         }
         for (RandomListNode* p = ptmp; p != nullptr; p = p->next)
         {
             if(p->random!=NULL)
                 hash_map[p]->random=hash_map[p->random];
         }
         return CopyHead;
    }
};

JAVA解法

/*
// Definition for a Node.
class Node {
    int val;
    Node next;
    Node random;

    public Node(int val) {
        this.val = val;
        this.next = null;
        this.random = null;
    }
}
*/
class Solution {
    public Node copyRandomList(Node head) {
        if(head == null){
            return null;
        }
        Node newHead = new Node(head.val);
        Node copyTmp = newHead; 
        Node oldTmp = head.next;
        Map<Node,Node> map = new HashMap<>();
        map.put(head,newHead);
        while(oldTmp!=null){
            copyTmp.next = new Node(oldTmp.val);
            copyTmp = copyTmp.next;
            map.put(oldTmp,copyTmp);
            oldTmp = oldTmp.next;
        }
        oldTmp = head;
        copyTmp = newHead;
        while(oldTmp!=null){
            if(oldTmp.random!=null){
                map.get(oldTmp).random = map.get(oldTmp.random);
            }
            oldTmp = oldTmp.next;
        }
        return newHead;
    }
}

思路：剑指offer上的

先复制，但是复制的每个指针都紧跟在后面连起来  CloneNode(pHead);

然后连接random指针                          ConnectRan(pHead);

最后拆开两个链表                               Resconn(pHead);

/*
struct RandomListNode {
    int label;
    struct RandomListNode *next, *random;
    RandomListNode(int x) :
            label(x), next(NULL), random(NULL) {
    }
};
*/
class Solution {
public:
    void CloneNode(RandomListNode* pHead)
    {
        RandomListNode* pNode=pHead;
        while(pNode!=NULL)
        {
            RandomListNode* tmp=new RandomListNode(pNode->label);
            tmp->next=pNode->next;
            tmp->random=NULL;
            pNode->next=tmp;
            pNode=tmp->next;
        }
    }
    void ConnectRan(RandomListNode* pHead)
    {
        RandomListNode* pNode=pHead;
        while(pNode!=NULL)
        {
            RandomListNode* tmp=pNode->next;
            if(pNode->random!=NULL)
                tmp->random=pNode->random->next;
            pNode=tmp->next;
        }
    }
    RandomListNode* Resconn(RandomListNode* pHead)
    {
        RandomListNode* pNode=pHead;
        RandomListNode* CloneHead=NULL;
        RandomListNode* CloneTmp=NULL;
        if(pNode!=NULL)
        {
            CloneHead=CloneTmp=pNode->next;
            pNode->next=CloneHead->next;
            pNode=pNode->next;
        }
        while(pNode!=NULL)
        {
            CloneTmp->next=pNode->next;
            CloneTmp=CloneTmp->next;
            pNode->next=CloneTmp->next;
            pNode=pNode->next;
        }
        return CloneHead;
    }
    RandomListNode* Clone(RandomListNode* pHead)
    {
        CloneNode(pHead);
        ConnectRan(pHead);
        return Resconn(pHead);
    }
};

JAVA解法

/*
// Definition for a Node.
class Node {
    int val;
    Node next;
    Node random;

    public Node(int val) {
        this.val = val;
        this.next = null;
        this.random = null;
    }
}
*/
class Solution {
    public Node copyRandomList(Node head) {
        if(head == null){
            return null;
        }
        Node newHead = cloneNode(head);
        cloneRandom(newHead);
        return splitList(newHead);
    }

    private Node cloneNode(Node head){
        Node tmp = head;
        while(tmp!=null){
            Node copyTmp = new Node(tmp.val);
            copyTmp.next = tmp.next;
            tmp.next = copyTmp;
            tmp = tmp.next.next;
        }
        return head;
    }

    private void cloneRandom(Node head){
        Node tmp = head;
        while(tmp!=null){
            if(tmp.random!=null){
                tmp.next.random = tmp.random.next;
            }
            tmp = tmp.next.next;
        }
    }

    private Node splitList(Node head){
        Node newHead = head.next;
        Node newTmp = newHead;
        Node oldTmp = head;
        oldTmp.next = newTmp.next;
        oldTmp = oldTmp.next;
        while(oldTmp!=null){
//这里要搞清楚关系，oldTmp要恢复原来链表的样子
            newTmp.next = oldTmp.next;
            newTmp = newTmp.next;
            oldTmp.next = newTmp.next;                
            oldTmp = oldTmp.next;
        }
        return newHead;
    }
}