Lintcode-medium-copy List with Random Pointer

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

Return a deep copy of the list.

Ideas:

First, according to the normal order, to get a copy of the linked list, while using a hashmap to establish the corresponding relationship between the old and new nodes, and then add the random pointer, so that the random pointer point to the node is always a new node has been established, will not be null

/*** Definition for singly-linked list with a random pointer. * Class Randomlistnode {* int label; * Randomlist Node Next, Random; * Randomlistnode (int x) {This.label = x;}}; */ Public classSolution {/**     * @paramhead:the head of linked list with a random pointer. * @return: A new head of a deep copy of the list. */     PublicRandomlistnode copyrandomlist (Randomlistnode head) {//Write your code here        if(Head = =NULL)            return NULL; Randomlistnode Newhead=NewRandomlistnode (Head.label); Randomlistnode P1=Head.next; Randomlistnode P2=Newhead; HashMap<randomlistnode, randomlistnode> map =NewHashmap<randomlistnode, randomlistnode>();                Map.put (head, newhead);  while(P1! =NULL) {P2.next=NewRandomlistnode (P1.label); P2=P2.next;            Map.put (P1, p2); P1=P1.next; } p1=Head; P2=Newhead;  while(P1! =NULL) {P2.random=Map.get (p1.random); P1=P1.next; P2=P2.next; }                returnNewhead; }}

Lintcode-medium-copy List with Random Pointer