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  1. #include <iostream>
  2.  
  3. template<typename F> unsigned fact(int i, F&& f) {
  4.     if(i == 0)
  5.         return 1;
  6.     return i * f(i - 1);
  7. }
  8. struct fact_doubler {
  9.     unsigned operator()(unsigned i) {
  10.         return 2 * fact(i, *this);
  11.     }
  12. };
  13. int main() {
  14.     fact_doubler f;
  15.     std::cout << f(5);
  16. }
Success #stdin #stdout 0s 2884KB
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https://ideone.com/JLRhx
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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