一、题目内容

二、题解

解法1：

思路

hashmap字典，遍历存储。

代码

class Solution {
    public Node copyRandomList(Node head) {
        if (head == null) {
            return head;
        }
        HashMap<Node, Node> dicMap = new HashMap<Node, Node>();
        Node curr = head;
        while (curr != null) {
            dicMap.put(curr, new Node(curr.val));
            curr = curr.next;
        }
        curr = head;
        while (curr != null) {
            dicMap.get(curr).next = dicMap.get(curr.next);
            dicMap.get(curr).random = dicMap.get(curr.random);
            curr = curr.next;
        }
        return dicMap.get(head);
    }
}

解法2：

思路

hashMap字典，递归存储。

代码

class Solution {
    private HashMap<Node, Node> dicMap = new HashMap<Node, Node>();
    public Node copyRandomList(Node head) {
        if (head == null) {
            return head;
        }
        if (dicMap.containsKey(head)) {
            return dicMap.get(head);
        }
        Node node = new Node(head.val);
        dicMap.put(head, node);
        node.next = copyRandomList(head.next);
        node.random = copyRandomList(head.random);
        return node;
    }
}