[数据结构与算法]链表-Java-力扣138. 复制带随机指针的链表

1. 题目

题目链接138. 复制带随机指针的链表

2. 思路

使用hashmap存储旧的节点和新的节点，然后利用旧节点的指向关系去构建新的节点的指向关系。

3. 代码

/*
// 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) {
        // 边界条件
        if (head == null) return head;
         
        // 使用map存储 然后取出来连接
        Map<Node, Node> hashMap = new HashMap();
        Node curr = head;
        while (curr != null) {
            Node node = new Node(curr.val);
            hashMap.put(curr, node);
            curr = curr.next;
        }

        // 依次取出来 然后连接
        curr = head;
        while (curr != null) {
            hashMap.get(curr).next = hashMap.get(curr.next);
            hashMap.get(curr).random = hashMap.get(curr.random);
            curr = curr.next;
        }
        return hashMap.get(head);
    }
}