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  1. #include <memory>
  2.  
  3. struct ListNode;
  4. using List = std::unique_ptr<const ListNode>;
  5.  
  6. struct ListNode {
  7.     const int data;
  8.     const List next;
  9. };
  10.  
  11. List Cons(int head, List tail)
  12. {
  13.     return List(new ListNode{head, std::move(tail)});
  14. }
  15.  
  16. List Nil()
  17. {
  18.     return List();
  19. }
  20.  
  21. size_t len(const List & self)
  22. {
  23.     if (!self) {
  24.         return 0;
  25.     }
  26.     return 1 + len(self->next);
  27. }
  28.  
  29. #include <iostream>
  30.  
  31. void test(size_t n)
  32. {
  33.     auto p = Nil();
  34.     for (size_t i = 0; i < n; ++i) {
  35.         auto x = std::move(p);
  36.         p = Cons(1, std::move(x));
  37.     }
  38.     std::cout << "done: " << len(p) << std::endl;
  39. }
  40.  
  41. int main()
  42. {
  43.     test(131028);
  44. }
Success #stdin #stdout 0.01s 6364KB
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stdin
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Standard input is empty
stdout
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done: 131028
https://ideone.com/li5sV3
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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