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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. // Definition for singly-linked list.
  5. struct ListNode {
  6.     int val;
  7.     ListNode* next;
  8.     ListNode(int x) : val(x), next(nullptr) {}
  9. };
  10.  
  11. class Solution {
  12. public:
  13.     ListNode* reverseList(ListNode* cur, ListNode* prev = nullptr) {
  14.         if (cur == nullptr) return prev;
  15.         ListNode* nxt = cur->next;
  16.         cur->next = prev;
  17.         return reverseList(nxt, cur);
  18.     }
  19. };
  20.  
  21. // Helper function to print the linked list
  22. void printList(ListNode* head) {
  23.     while (head != nullptr) {
  24.         cout << head->val << " -> ";
  25.         head = head->next;
  26.     }
  27.     cout << "NULL" << endl;
  28. }
  29.  
  30. // Helper function to create a linked list from an array
  31. ListNode* createList(int arr[], int n) {
  32.     if (n == 0) return nullptr;
  33.     ListNode* head = new ListNode(arr[0]);
  34.     ListNode* current = head;
  35.     for (int i = 1; i < n; ++i) {
  36.         current->next = new ListNode(arr[i]);
  37.         current = current->next;
  38.     }
  39.     return head;
  40. }
  41.  
  42. int main() {
  43.     int arr[] = {1, 2, 3, 4, 5};
  44.     int n = sizeof(arr) / sizeof(arr[0]);
  45.  
  46.     // Create the linked list
  47.     ListNode* head = createList(arr, n);
  48.  
  49.     cout << "Original list: ";
  50.     printList(head);
  51.  
  52.     // Reverse the list
  53.     Solution sol;
  54.     ListNode* reversed = sol.reverseList(head);
  55.  
  56.     cout << "Reversed list: ";
  57.     printList(reversed);
  58.  
  59.     return 0;
  60. }
  61.  
Success #stdin #stdout 0.01s 5288KB
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stdin
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Standard input is empty
stdout
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Original list: 1 -> 2 -> 3 -> 4 -> 5 -> NULL
Reversed list: 5 -> 4 -> 3 -> 2 -> 1 -> NULL
https://ideone.com/sNv636
language:
C++14 (gcc 8.3)
created:
12 days ago
visibility:
public

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