标签：blog class 链表 list logs dom add return map
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.
解法一：用一个map把原有的节点映射到新建的对象。遍历两遍，第一次新复制一个原有的链表，第二次做random的映射。时间复杂度O(n),空间复杂度O(n).
/** * Definition for singly-linked list with a random pointer. * struct RandomListNode { * int label; * RandomListNode *next, *random; * RandomListNode(int x) : label(x), next(NULL), random(NULL) {} * }; */ class Solution { public: RandomListNode *copyRandomList(RandomListNode *head) { if(!head)return {}; map<RandomListNode*, RandomListNode*>hash; RandomListNode *res=NULL, *orig=head, *tail=NULL; while(head){ RandomListNode* temp=new RandomListNode(head->label); if(!tail)res=tail=temp; else tail->next=temp,tail=tail->next; hash[head]=temp; head=head->next; } tail=res; while(orig){ tail->random=hash[orig->random]; tail=tail->next; orig=orig->next; } //tail->next=NULL; return res; } };
解法二：在原有每个节点之后都插入一个新的节点，这样原有的节点都是新节点的pre，这样每次新的random都是前一个节点的random，最后再把这些新建的节点摘除下来，就是最后的结果。
/** * Definition for singly-linked list with a random pointer. * struct RandomListNode { * int label; * RandomListNode *next, *random; * RandomListNode(int x) : label(x), next(NULL), random(NULL) {} * }; */ class Solution { public: RandomListNode *copyRandomList(RandomListNode *head) { if(!head)return {}; RandomListNode *orig=head, *copy; //insert new nodes after origin nodes while(head){ copy=new RandomListNode(head->label); copy->next=head->next; head->next=copy; head=copy->next; } head=orig; while(head){ copy=head->next; if(head->random) copy->random=head->random->next; head=copy->next; } RandomListNode *res=orig->next; head=orig; while(head){ copy=head->next; head->next=copy->next; head=head->next; copy->next=head?head->next:NULL; } return res; } };
138. Copy List with Random Pointer
标签：blog class 链表 list logs dom add return map
原文地址：http://www.cnblogs.com/tsunami-lj/p/7631510.html
