[leetCode] Copy List with Random Pointer

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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.

 

思路：首先將新節點串連到所複製的節點後面，再這樣的鏈表上處理random指標。

　　　時間複雜度O(n),空間複雜度O(1)

 1 /** 2  * Definition for singly-linked list with a random pointer. 3  * struct RandomListNode { 4  *     int label; 5  *     RandomListNode *next, *random; 6  *     RandomListNode(int x) : label(x), next(NULL), random(NULL) {} 7  * }; 8  */ 9 class Solution {10 public:11     RandomListNode *copyRandomList(RandomListNode *head) {12         if (head == NULL) return head;13         14         15         for (RandomListNode *curr = head; curr != NULL;) {16             RandomListNode *pter = new RandomListNode(curr->label);17             pter->next = curr->next;18             curr->next = pter;19             curr = pter->next;20         }21         22         //連結rando指標23         for(RandomListNode *curr = head; curr != NULL;) {24             if (curr->random != NULL) {25                 curr->next->random = curr->random->next;26             }27             curr = curr->next->next;28         }29         30         //分拆鏈表31         RandomListNode *new_head = head->next;32         for (RandomListNode *curr = head, **new_curr = &new_head; curr != NULL;) {33             *new_curr = curr->next;34             curr->next = curr->next->next;35             36             curr = curr->next;37             38             new_curr = &((*new_curr)->next);39         }40         41         return new_head;42     }43 };

 

[leetCode] Copy List with Random Pointer