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  1. #include <iostream>
  2. #include <algorithm>
  3. #include <iterator>
  4. #include <vector>
  5. #include <stdexcept>
  6.  
  7. template<typename InputIt, typename OutputIt>
  8. OutputIt copy_every_nth(InputIt first, InputIt last, OutputIt d_first, size_t nth) {
  9.   if (nth == 0) {
  10.     throw std::invalid_argument("copy_nth: nth can't be 0");
  11.   }    
  12.  
  13.   size_t counter = 0;
  14.  
  15.   auto pred = [&counter, nth]
  16.   (const typename std::iterator_traits<InputIt>::value_type &) -> bool {
  17.  
  18.     return !(counter++ % nth);
  19.   };
  20.  
  21.   return std::copy_if(first, last, d_first, pred);
  22. }
  23.  
  24. int main() {
  25.   size_t nth = 0;
  26.  
  27.   std::cin >> nth;
  28.  
  29.   std::vector<int> v1 = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
  30.   std::vector<int> v2;
  31.  
  32.   copy_every_nth(v1.begin(), v1.end(), std::back_inserter(v2), nth);
  33.  
  34.   std::copy(v2.begin(), v2.end(), std::ostream_iterator<int>(std::cout, " "));
  35.  
  36.   return 0;
  37. }
Success #stdin #stdout 0s 3068KB
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stdin
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2
stdout
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0 2 4 6 8
https://ideone.com/I7wKSl
language:
C++14 (gcc 8.3)
created:
13 years ago
visibility:
public

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