[leetcode]138 Copy List with Random Pointer

https://oj.leetcode.com/problems/copy-list-with-random-pointer/

http://blog.csdn.net/linhuanmars/article/details/22463599

/** * definition for singly-linked list with a random pointer.  * class RandomListNode { *     int label; *      RandomListNode next, random; *      Randomlistnode (int x)  { this.label = x; } * }; */public  Class solution {    public randomlistnode copyrandomlist ( Randomlistnode head)     {        if  ( Head == null)             return  null;                map< Randomlistnode, randomlistnode> map = new hashmap<> ();         randomlistnode old = head;        RandomListNode precopied =  null;        while  (old != null)          {            //  copy            randomlistnode copied  = new randomlistnode (Old.label);             if  (precopied != null)                  precopied.next = copied;             precopied = copied;             map.put (old, copied);                         old = old.next;         }                 randomlistnode newhead = map.get (head);         while  (head != null)         {             map.get (head). Random = map.get (Head.random);             head = head.next;         }                 return newhead;    }    }

[leetcode]138 Copy List with Random Pointer