[JAVA]deep copy链表

deep copy的意思我觉得就是复制一个对象成为新的对象，和原来的对象有不同的内存地址，不是简单的引用复制。

题目来源：leetcode

题目描述：

Copy List with Random Pointer

A linked list is given such that each node contains an additional random pointer which could point to any node in the list or null.

Return a deep copy of the list.

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最简单的办法就是先把所有都复制一遍，然后重新给他的next和radom赋值。实际上直接在当前结点的后面复制会比在map中复制更加快，但是放到map感觉更加形象的解释deepcopy的概念

/*
// Definition for a Node.
class Node {
    public int val;
    public Node next;
    public Node random;

    public Node() {}

    public Node(int _val,Node _next,Node _random) {
        val = _val;
        next = _next;
        random = _random;
    }
};
*/
class Solution {
    public Node copyRandomList(Node head) {
        Map<Node,Node> m=new HashMap<Node,Node>();
        Node cur=head;
        while(cur!=null)
        {
            m.put(cur,new Node(cur.val,null,null));
            cur=cur.next;
        }
        cur=head;
        while(cur!=null)
        {
            m.get(cur).next=m.get(cur.next);
            m.get(cur).random=m.get(cur.random);
            cur=cur.next;
        }
        return m.get(head);
    }
}