138. 复制带随机指针的链表

题目链接：https://leetcode-cn.com/problems/copy-list-with-random-pointer/

class Solution {
    func copyRandomList(_ head: Node?) -> Node? {
        var dict = [Node:Node]()

        func copy(_ node: Node?) -> Node? {
            guard let node = node else {
                return nil
            }
            if dict[node] == nil {
                let newHead = Node(node.val)
                dict[node] = newHead
                newHead.next = copy(node.next)
                newHead.random = copy(node.random)
            }
            return dict[node]
        }
        return copy(head)
    }
}

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

执行用时：176 ms, 在所有 Kotlin 提交中击败了100.00% 的用户
内存消耗：34.6 MB, 在所有 Kotlin 提交中击败了100.00% 的用户

class Solution {
    fun copyRandomList(node: Node?): Node? {
        if (node == null) {
            return null
        }
        var cur = node
        var map = HashMap <Node?, Node?>()
        while (cur != null) {
            map[cur] = Node(cur.`val`)
            cur = cur.next
        }
        cur = node
        while (cur != null) {
            var temp = map[cur]!!
            temp.next = map[cur.next]
            temp.random = map[cur.random]
            cur = cur.next
        }
        return map[node]
    }
}