138. 复制带随机指针的链表

### 解题思路

和克隆图133是一个思路,利用哈希表保存每个节点克隆出来的节点,边遍历边克隆

### 代码

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