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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. struct ListNode
  5. {
  6.     int val;
  7.     ListNode *next;
  8.     ListNode() : val(0), next(nullptr) {}
  9.     ListNode(int x) : val(x), next(nullptr) {}
  10.     ListNode(int x, ListNode *next) : val(x), next(next) {}
  11. };
  12.  
  13. ListNode* cloneList(ListNode* head) {
  14.     if (!head) return NULL; // <-- add this
  15.     ListNode *prev = new ListNode(head->val);
  16.     head = head->next;
  17.     while (head != NULL)
  18.     {
  19.         ListNode *p = new ListNode(head->val, prev);
  20.         head = head->next;
  21.         prev = p;
  22.     }
  23.     return prev;
  24. }
  25.  
  26. void printList(ListNode* head) {
  27. 	while (head)
  28. 	{
  29. 		cout << head->val << " ";
  30. 		head = head->next;
  31. 	}
  32. 	cout << "\n";
  33. }
  34.  
  35. void freeList(ListNode* head) {
  36. 	while (head)
  37. 	{
  38. 		ListNode *n = head->next;
  39. 		delete head;
  40. 		head = n;
  41. 	}
  42. }
  43.  
  44. int main() {
  45.  
  46. 	ListNode *head = nullptr;
  47. 	ListNode **ptr = &head;
  48. 	for(int i = 1; i <= 5; ++i)
  49. 	{
  50. 		*ptr = new ListNode(i);
  51. 		ptr = &((*ptr)->next);
  52. 	}
  53.  
  54. 	printList(head);
  55.  
  56. 	ListNode *clone = cloneList(head);
  57.  
  58. 	printList(clone);
  59.  
  60. 	freeList(head);
  61. 	freeList(clone);
  62. 	return 0;
  63. }
Success #stdin #stdout 0.01s 5380KB
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Standard input is empty
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1 2 3 4 5 
5 4 3 2 1
https://ideone.com/wS5gtx
language:
C++ 4.3.2 (gcc-4.3.2)
created:
3 years ago
visibility:
public

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