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leetcode[138] Copy List with Random Pointer

这里是复制带有一个random指针的链表。是不是很熟悉啊。之前有做过克隆无向图的。那就借助leetcode Clone Graph的思路。

分两次遍历链表,一次先复制普通的含next的,另一次就是复制random了。利用map记录,可以一次就找到想要的点。

/** * 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 head;        RandomListNode *pre = new RandomListNode(0), *proc = head, *root = pre, *tmp_pre = pre;        unordered_map<RandomListNode *, RandomListNode*> umap;        while (proc)        {            root -> next = new RandomListNode(proc -> label);            umap[proc] = root -> next;            proc = proc -> next;            root = root -> next;        }        while (head)        {            tmp_pre -> next -> random = umap[head -> random];            head = head -> next;            tmp_pre = tmp_pre -> next;        }        return pre -> next;    }};

 

leetcode[138] Copy List with Random Pointer