再帰でやってみた #include <string> // std::string #include <functional> // std::function std::string binary(int dec) { std::function<std::string(int)> base2 = [&](int val) { if(val == 0) return std::string{}; return base2(val >> 1) + std::to_string(val%2); }; if(dec == 0) retu</std::string(int)></functional></string>…