标签：order list col ble http new return and 建立
题目描述：
2.3 138. Copy List with Random Pointer
https://leetcode.com/problems/copy-list-with-random-pointer/#/description
思路：建立两个节点，哨兵节点最后返回结果，一个随着计算进行next，首先只要当前节点不为空，就不断将node压入一个哈希表unordered_map，这个map里面可以是原来表的node，value是新的node，接下来的循环是拷贝随机指针，Map[tmp] -> random = Map[tmp -> random];
/* struct RandomListNode { int label; struct RandomListNode *next, *random; RandomListNode(int x) : label(x), next(NULL), random(NULL) { } }; */ class Solution { public: RandomListNode* Clone(RandomListNode* pHead){ if(pHead == nullptr){ return nullptr; } unordered_map<RandomListNode*,RandomListNode*> old2new; RandomListNode* oldHead = pHead; RandomListNode* tmp = pHead; RandomListNode* newHead = new RandomListNode(-1); RandomListNode* newTmpHead = newHead; while(oldHead != nullptr){ RandomListNode* newNode = new RandomListNode(oldHead -> label); old2new[oldHead] = newNode; oldHead = oldHead -> next; newHead -> next = newNode; newHead = newHead -> next; } while(tmp != nullptr){ if(tmp -> random != nullptr){ old2new[tmp] -> random = old2new[tmp -> random]; } tmp = tmp -> next; } return newTmpHead -> next; } };
上面的时间复杂度和空间复杂度都是O(n)。
剑指offer150页优化了空间复杂度为O(1)，时间复杂度为O(n)。
三步走进行复制。
标签：order list col ble http new return and 建立
原文地址：http://www.cnblogs.com/dingxiaoqiang/p/7471213.html
