网站建设wordpress比较今日热点新闻2022

题目链接：

链接

题目描述：

思路：

思路一

利用map，先把val复制到新的node，再把关系复制到node，
key是旧的node，value是新的node

思路二

不复制在map里，而是直接复制在链表里，相当于插入一个新的node，插入后就会知道原本节点的next，但是不知道random，所以还需要再遍历一次找到random，最后拆分两个链表

实现代码：

class Solution {public Node copyRandomList(Node head) {Node cur = head;Map<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);}
}

class Solution {public Node copyRandomList(Node head) {if(head==null){return head;}//复制插入Node cur = head;while(cur != null){Node tmp = cur.next;cur.next = new Node(cur.val);cur.next.next = tmp;cur = tmp;}//找randomcur = head;while(cur != null){if(cur.random != null){cur.next.random = cur.random.next;}cur = cur.next.next;}//拆分Node ans = head.next, pre = head;cur = head.next;while(cur.next != null){pre.next = pre.next.next;cur.next = cur.next.next;pre = pre.next;cur = cur.next;}pre.next = null;return ans;}
}