hoge.cpp

#include <iostream>
#include <vector>

template <class T>
concept LikeArray = requires (T&& arr) {
  arr[0];
  std::size(arr);
  std::begin(arr);
  std::end(arr);
};

template <class T> requires LikeArray<T>
void reverse(T& arr) {
  const int N = std::size(arr);
  for (int i = 0; i < N / 2; i++) {
    std::swap(arr[i], arr[N - i - 1]);
  }
}

template<class T> requires LikeArray<T>
void print_array(const T& arr){
  for (auto it = std::begin(arr); it < std::end(arr); it++) {
    std::cout << *it << std::endl;
  }
}

int main(int ac, char **av) {
  std::vector<int> vec {1, 2, 3};
  reverse(vec);
  print_array(vec);

  std::cout << std::endl << "=====" << std::endl << std::endl;

  int array[] = {1, 2, 3, 4, 5, 6};
  reverse(array);
  print_array(array);
}