LeetCode 138. Copy a linked list with random pointers

原题网址：https://leetcode.cn/problems/copy-list-with-random-pointer/submissions/

给一个链表,Make a deep copy of the linked list.
使用mapsave copy;Then you can get the current nodenext,random的拷贝节点;Reorganize its relationship;

    // Similar to the idea of ​​deep clone graph,mapSave a copy in,
    // 两次遍历,The first traversal constitutes the linked list,The second pass is sorting random pointers
    public Node copyRandomList(Node head) {
    

        Map<Node,Node> map = new HashMap<>();

        Node cur = head;
        while(cur != null) {
    
            map.put(cur, new Node(cur.val));
            cur = cur.next;
        }
        cur = head;
        while(cur != null) {
    
        	// The node to which the current node is associated
            Node next = cur.next;
            Node random = cur.random;
	
			// Get the copy node of the associated node;
			// in organizing its relationships;
            Node copy = map.get(cur);
            copy.next = map.get(next);
            copy.random = map.get(random);

            cur = cur.next;
        }
        return map.get(head);
       
    }