Can I get just the counts from combinations_with_replacement ? #56

Activity

1. ryanhaining

   added

   question

   on Mar 24, 2019
2. ryanhaining commented on Mar 24, 2019

   

   ryanhaining

   on Mar 24, 2019

   Owner

   More actions

   Without iterating through at all, I don't think so. With just printing them I have:

   #include "cppitertools/combinations_with_replacement.hpp"
   
   #include <iostream>
   #include <vector>
   
   int main() {
     const std::vector<int> v = {3, 7};
     for (auto &&ns : iter::combinations_with_replacement(v, 4)) {
       std::cout << "{ ";
       for (auto i : v) {
         std::cout << std::count(ns.begin(), ns.end(), i) << ' ';
       }
       std::cout << "}\n";
     }
   }

   For one object that you can iterate through:

   #include "cppitertools/combinations_with_replacement.hpp"
   #include "cppitertools/imap.hpp"
   
   #include <iostream>
   #include <vector>
   
   int main() {
     const std::vector<int> v = {3, 7};
   
     auto counts = iter::imap([&v](auto&& ns) {
         return iter::imap([&ns](auto i) {
             return std::count(std::begin(ns), std::end(ns), i);
         }, v);
     }, iter::combinations_with_replacement(v, 4));
   
     // then to iterate over it and display
     for (auto&& c : counts) {
       std::cout << "{ ";
       for (auto i : c) {
         std::cout << i << ' ';
       }
       std::cout << "}\n";
     }
   }

   The above still iterates through it with the call to std::count of course.