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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. // Node structure
  5. struct Node {
  6.     int data;
  7.     Node* next;
  8.     Node(int val) : data(val), next(nullptr) {}
  9. };
  10.  
  11. class Solution {
  12. public:
  13.     Node* reverse(Node* head) {
  14.         Node* cur = head, *prev = nullptr, *nxt = nullptr;
  15.         while (cur) {
  16.             nxt = cur->next;
  17.             cur->next = prev;
  18.             prev = cur;
  19.             cur = nxt;
  20.         }
  21.         return prev;
  22.     }
  23.  
  24.     Node* addOne(Node* head) {
  25.         head = reverse(head);
  26.         Node* cur = head;
  27.         int carry = 1;
  28.  
  29.         while (cur) {
  30.             int sum = cur->data + carry;
  31.             cur->data = sum % 10;
  32.             carry = sum / 10;
  33.  
  34.             if (!cur->next && carry) {
  35.                 cur->next = new Node(carry);
  36.                 break;
  37.             }
  38.             cur = cur->next;
  39.         }
  40.  
  41.         return reverse(head);
  42.     }
  43. };
  44.  
  45. // Helper to print the list
  46. void printList(Node* head) {
  47.     while (head) {
  48.         cout << head->data;
  49.         head = head->next;
  50.     }
  51.     cout << endl;
  52. }
  53.  
  54. // Helper to create linked list from digits
  55. Node* createList(const string& number) {
  56.     Node* head = new Node(number[0] - '0');
  57.     Node* current = head;
  58.     for (size_t i = 1; i < number.size(); ++i) {
  59.         current->next = new Node(number[i] - '0');
  60.         current = current->next;
  61.     }
  62.     return head;
  63. }
  64.  
  65. int main() {
  66.     string num = "1299";  // example input number
  67.     Node* head = createList(num);
  68.  
  69.     cout << "Original number: ";
  70.     printList(head);
  71.  
  72.     Solution sol;
  73.     Node* result = sol.addOne(head);
  74.  
  75.     cout << "After adding one: ";
  76.     printList(result);
  77.  
  78.     return 0;
  79. }
  80.  
Success #stdin #stdout 0s 5292KB
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stdin
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Standard input is empty
stdout
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Original number: 1299
After adding one: 1300
https://ideone.com/tKVe2x
language:
C++14 (gcc 8.3)
created:
12 days ago
visibility:
public

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