1 #include <iostream>

 2 using namespace std;

 3

 4 struct ListNode {

 5     int val;

 6     ListNode *next;

 7     ListNode(int x) : val(x), next(NULL) {}

 8 };

 9

10 ListNode* createLinkedList(int arr[], int n){

11     if( n == 0 )

12         return NULL;

13     ListNode* head = new ListNode(arr[0]);

14     ListNode* curNode = head;

15     for( int i = 1 ; i < n ; i ++ ){

16         curNode->next = new ListNode(arr[i]);

17         curNode = curNode->next;

18     }

19     return head;

20 }

21

22 void printLinkedList(ListNode* head){

23     ListNode* curNode = head;

24     while( curNode != NULL ){

25         cout << curNode->val << " -> ";

26         curNode = curNode->next;

27     }

28     cout<<"NULL"<<endl;

29     return;

30 }

31

32 void deleteLinkedList(ListNode* head){

33     ListNode* curNode = head;

34     while( curNode != NULL){

35         ListNode* delNode = curNode;

36         curNode = curNode->next;

37         delete delNode;

38     }

39     return;

40 }

41

42 class Solution {

43 public:

44     ListNode* reverseList(ListNode* head) {

45

46         ListNode* pre = NULL;

47         ListNode* cur = head;

48         while( cur != NULL){

49             ListNode* next = cur->next;

50             cur->next = pre;

51             pre = cur;

52             cur = next;

53         }

54         return pre;

55     }

56 };

57

58 int main(){

59     int arr[] = {1,2,3,4,5};

60     int n = sizeof(arr)/sizeof(int);

61

62     ListNode* head = createLinkedList(arr,n);

63     printLinkedList(head);

64

65     ListNode* head2 = Solution().reverseList(head);

66     printLinkedList(head2);

67

68     deleteLinkedList(head2);

69     return 0;

70 }