Leetcode 138. 随机链表的复制 哈希 / 拼接+拆分

原题链接：添加链接描述

哈希：

/*
// Definition for a Node.
class Node {
public:
    int val;
    Node* next;
    Node* random;
    
    Node(int _val) {
        val = _val;
        next = NULL;
        random = NULL;
    }
};
*/

class Solution {
public:
    Node* copyRandomList(Node* head) {
        if(head==NULL) return NULL;
        Node* cur = head;
        unordered_map<Node*,Node*> mp;
        while(cur!=NULL){
            mp[cur]=new Node(cur->val);
            cur=cur->next;
        }
        cur = head;
        while(cur!=NULL){
            mp[cur]->next = mp[cur->next];
            mp[cur]->random = mp[cur->random];
            cur=cur->next;
        }
        return mp[head];
    }
};

拼接+拆分：

/*
// Definition for a Node.
class Node {
public:
    int val;
    Node* next;
    Node* random;
    
    Node(int _val) {
        val = _val;
        next = NULL;
        random = NULL;
    }
};
*/

class Solution {
public:
    Node* copyRandomList(Node* head) {
        if(head==NULL) return NULL;
        Node* cur = head;
        while(cur!=NULL){
            Node* cur_copy = new Node(cur->val);
            cur_copy->next = cur->next;
            cur_copy->random = NULL;
            cur->next = cur_copy;
            cur = cur_copy->next;
        }
        cur = head;
        while(cur!=NULL){
            Node* random = cur->random;
            Node* cur_copy = cur->next;
            if(random!=NULL) cur_copy->random = random->next;
            cur = cur_copy->next;
        }
        Node* node = head->next;
        Node* pre = node;
        int cnt=0;
        cur = head;
        while(cur!=NULL){
            Node* cur_copy = cur->next;
            cur->next = cur_copy->next;
            if(cnt){
                pre->next = cur_copy;
                pre= cur_copy;
            }
            cnt++;
            cur = cur->next;
        }
        return node;
    }
};