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面试题 35. 复杂链表的复制

题目描述

请实现 copyRandomList 函数，复制一个复杂链表。在复杂链表中，每个节点除了有一个 next 指针指向下一个节点，还有一个 random 指针指向链表中的任意节点或者 null。

示例 1：

输入：head = [[7,null],[13,0],[11,4],[10,2],[1,0]]
输出：[[7,null],[13,0],[11,4],[10,2],[1,0]]

示例 2：

输入：head = [[1,1],[2,1]]
输出：[[1,1],[2,1]]

示例 3：

输入：head = [[3,null],[3,0],[3,null]]
输出：[[3,null],[3,0],[3,null]]

示例 4：

输入：head = []
输出：[]
解释：给定的链表为空（空指针），因此返回 null。

提示：

• -10000 <= Node.val <= 10000
• Node.random  为空（null）或指向链表中的节点。
• 节点数目不超过 1000 。

解法

Python3

"""
# Definition for a Node.
class Node:
    def __init__(self, x: int, next: 'Node' = None, random: 'Node' = None):
        self.val = int(x)
        self.next = next
        self.random = random
"""
class Solution:
    def copyRandomList(self, head: 'Node') -> 'Node':
        if not head:
            return None
        copy_head = Node(-1)
        cur, t = copy_head, head
        cache = {}
        while t:
            cur.next = Node(t.val)
            cache[t] = cur.next
            cur, t = cur.next, t.next
        t, cur = head, copy_head.next
        while t:
            cur.random = cache.get(t.random)
            cur, t = cur.next, t.next
        return copy_head.next

Java

/*
// 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;
        }
        Map<Node, Node> map = new HashMap<>();
        Node copyHead = new Node(-1);
        Node cur = copyHead, t = head;
        while (t != null) {
            Node node = new Node(t.val);
            map.put(t, node);
            cur.next = node;
            cur = node;
            t = t.next;
        }
        cur = copyHead.next;
        while (head != null) {
            cur.random = map.get(head.random);
            cur = cur.next;
            head = head.next;
        }
        return copyHead.next;

    }
}

JavaScript

/**
 * // Definition for a Node.
 * function Node(val, next, random) {
 *    this.val = val;
 *    this.next = next;
 *    this.random = random;
 * };
 */
/**
 * @param {Node} head
 * @return {Node}
 */
var copyRandomList = function (head) {
  function copy(node) {
    if (!node) return null;
    if (isRead.get(node)) return isRead.get(node);
    let newNode = new Node(node.val);
    isRead.set(node, newNode);
    newNode.random = copy(node.random);
    newNode.next = copy(node.next);
    return newNode;
  }
  let isRead = new Map();
  return copy(head);
};

Go

func copyRandomList(head *Node) *Node {
    if head == nil {
        return nil
    }
    cur, next := head,head
    //完成对当前节点的复制
    for cur != nil {
        next = cur.Next
        cur.Next = &Node{
            Val: cur.Val,
            Next: next,
            Random: nil,
        }
        cur = next
    }
    //设置复制节点的random节点
    cur = head
    curCopy := head
    for cur != nil {
        next = cur.Next.Next
        curCopy = cur.Next
        if cur.Random == nil {
            curCopy.Random = nil
        } else {
            curCopy.Random = cur.Random.Next
        }
        cur = next
    }
    res := head.Next
    cur = head
    for cur != nil {
        next = cur.Next.Next
        curCopy = cur.Next
        cur.Next = next
        if next != nil {
            curCopy.Next = next.Next
        } else {
            curCopy.Next = nil
        }
        cur = cur.Next
    }
    return res
}

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