src/Binomial.cc

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#include<iostream>
#ifdef N
const unsigned n=N;
#undef N
#else
#error Constant integer N must be defined, use -DN=[n] option
const unsigned n=0; // to avoid further compiler errors
#endif


namespace my_lib {

  template<unsigned N, unsigned K>
  struct Binomial;

  template<bool T,unsigned N, unsigned K>
  struct CondBinom {
    static const unsigned val=Binomial<N-1,K-1>::val + Binomial<N-1,K>::val;
  };

  template<unsigned N, unsigned K>
  struct CondBinom<false,N,K> {
    static const unsigned val=0;
  };

  template<unsigned N, unsigned K>
  struct Binomial {
    static const unsigned val=CondBinom<(N>=K),N,K>::val;
  };

  template<unsigned N>
  struct Binomial<N,0> {
    static const unsigned val=1;
  };

  template<unsigned N>
  struct Binomial<N,N> {
    static const unsigned val=1;
  };

  template<>
  struct Binomial<0,0> {
    static const unsigned val=1;
  };



  template<unsigned K, unsigned N>
  struct Loop {
    static void print(){
      std::cout << Binomial<N,K>::val << std::endl;
      Loop<K+1,N>::print();
    }
  };

  template<unsigned N>
  struct Loop<N,N> {
    static void print(){
      std::cout << Binomial<N,N>::val << std::endl;
    }
  };

}

using namespace my_lib;
int main(){
  Loop<0,n>::print();
}