text: #ifndef HACKERRANK_EULER_040_H_
  #define HACKERRANK_EULER_040_H_
  
  #include <vector>
  #include <cstdint>
  
  // https://www.hackerrank.com/contests/projecteuler/challenges/euler040/problem
  
  struct P040_ChampernowneConstant
  {
  	P040_ChampernowneConstant();
  
  	uint32_t Solve(const uint64_t (&digits)[7]);
  
  	static void main();
  private:
  	std::vector<uint64_t> digit_bases;;
  	std::vector<uint64_t> num_bases;
  };
  
  #endif // HACKERRANK_EULER_040_H_
  