Leetcode-Copy List with Random Pointer

標籤：style   blog   io   color   sp   for   on   div   log   

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.

Solution:

 1 /** 2  * Definition for singly-linked list with a random pointer. 3  * class RandomListNode { 4  *     int label; 5  *     RandomListNode next, random; 6  *     RandomListNode(int x) { this.label = x; } 7  * }; 8  */ 9 public class Solution {10     public RandomListNode copyRandomList(RandomListNode head) {11         Map<RandomListNode,RandomListNode> map = new HashMap<RandomListNode,RandomListNode>();12         if (head==null) return null;13 14         RandomListNode head2 = new RandomListNode(head.label);15         map.put(head,head2);16         RandomListNode cur = head2;17 18         while (head!=null){19             RandomListNode rand1 = head.random;20             if (rand1!=null && map.containsKey(rand1)){21                 cur.random = map.get(rand1);22             } else if (rand1!=null) {23                 RandomListNode rand2 = new RandomListNode(rand1.label);24                 map.put(rand1,rand2);25                 cur.random = rand2;26             }27 28             if (head.next==null){29                 cur.next=null;30             } else {31                 RandomListNode next = head.next;32                 if (map.containsKey(next))33                     cur.next = map.get(next);34                 else {35                     RandomListNode next2 = new RandomListNode(next.label);36                     cur.next = next2;37                     map.put(next,next2);38                 }39             }40 41             head = head.next;42             cur = cur.next;43         }44 45         return head2;        46     }47 }

 

Leetcode-Copy List with Random Pointer