Task: Vampire number


C++: #include <vector>
#include <utility>
#include <algorithm>
#include <iostream>
#include <sstream>
#include <string>
#include <cmath>
 
bool isVampireNumber( long number, std::vector<std::pair<long, long> > & solution ) {
   std::ostringstream numberstream ;
   numberstream << number ;
   std::string numberstring( numberstream.str( ) ) ;
   std::sort ( numberstring.begin( ) , numberstring.end( ) ) ;
   int fanglength = numberstring.length( ) / 2 ;
   long start = static_cast<long>( std::pow( 10 , fanglength - 1 ) ) ;
   long end = sqrt(number) ;
   for ( long i = start ; i <= end ; i++ ) { 
      if ( number % i == 0 ) {
	 long quotient = number / i ;
	 if ( ( i % 10 == 0 ) && ( quotient % 10 == 0 ) ) 
	    continue ;
	 numberstream.str( "" ) ; 
	 numberstream << i << quotient ;
	 std::string divisorstring ( numberstream.str( ) ) ;
         std::sort ( divisorstring.begin( ) , divisorstring.end( ) ) ;
	 if ( divisorstring == numberstring ) {
	    std::pair<long , long> divisors = std::make_pair( i, quotient ) ;
	    solution.push_back( divisors ) ;
	 }
      }
   }
   return !solution.empty( ) ;
}
 
void printOut( const std::pair<long, long> & solution ) {
   std::cout << "[ " << solution.first << " , " << solution.second << " ]" ;
}
 
int main( ) {
   int vampireNumbersFound = 0 ;
   std::vector<std::pair<long , long> > solutions ;
   double i = 1.0 ;
   while ( vampireNumbersFound < 25 ) {
      long start = static_cast<long>( std::pow( 10 , i ) ) ;
      long end = start * 10 ;
      for ( long num = start ; num < end ; num++ ) {
	 if ( isVampireNumber( num , solutions ) ) {
            vampireNumbersFound++ ;
	    std::cout << vampireNumbersFound << " :" << num << " is a vampire number! These are the fangs:\n" ;
	    std::for_each( solutions.begin( ) , solutions.end( ) , printOut ) ;
	    std::cout << "\n_______________" << std::endl ;
	    solutions.clear( ) ;	    
	    if ( vampireNumbersFound == 25 ) 
	       break ;
	 }
      }
      i += 2.0 ;
   }
   std::vector<long> testnumbers ;
   testnumbers.push_back( 16758243290880 ) ;
   testnumbers.push_back( 24959017348650 ) ;
   testnumbers.push_back( 14593825548650 ) ;
   for ( std::vector<long>::const_iterator svl = testnumbers.begin( ) ; 
	 svl != testnumbers.end( ) ; svl++ ) {
      if ( isVampireNumber( *svl , solutions ) ) {
	 std::cout << *svl << " is a vampire number! The fangs:\n" ;
	 std::for_each( solutions.begin( ) , solutions.end( ) , printOut ) ;
	 std::cout << std::endl ;
	 solutions.clear( ) ;
      } else {
	 std::cout << *svl << " is not a vampire number!" << std::endl ;
      }
   }
   return 0 ;
}


C#: using System;

namespace RosettaVampireNumber
{
    class Program
    {
        static void Main(string[] args)
        {
            int i, j, n;
            ulong x;
            var f = new ulong[16];
            var bigs = new ulong[] { 16758243290880UL, 24959017348650UL, 14593825548650UL, 0 };
            ulong[] tens = new ulong[20];
            tens[0] = 1;
            for (i = 1; i < 20; i++)
                tens[i] = tens[i - 1] * 10;
            
            for (x = 1, n = 0; n < 25; x++)
            {
                if ((j = fangs(x, f, tens)) == 0) continue;
                Console.Write(++n + ": ");
                show_fangs(x, f, j);
            }

            Console.WriteLine();
            for (i = 0; bigs[i] > 0 ; i++)
            {
                if ((j = fangs(bigs[i], f, tens)) > 0)
                    show_fangs(bigs[i], f, j);
                else
                    Console.WriteLine(bigs[i] + " is not vampiric.");
            }
            Console.ReadLine();
        }

        private static void show_fangs(ulong x, ulong[] f, int cnt)
        {
            Console.Write(x); 
            int i;
            for (i = 0; i < cnt; i++)
                Console.Write(" = " + f[i] + " * " + (x / f[i]));
            Console.WriteLine();
        }

        private static int fangs(ulong x, ulong[] f, ulong[] tens)
        {
            int n = 0;
            int nd = ndigits(x);
            if ((nd & 1) > 0) return 0;
            nd /= 2;

            ulong lo, hi;
            lo = Math.Max(tens[nd - 1], (x + tens[nd] - 2) / (tens[nd] - 1));
            hi = Math.Min(x / lo, (ulong) Math.Sqrt(x));

            ulong a, b, t = dtally(x);
            for (a = lo; a <= hi; a++)
            {
                b = x / a;
                if (a * b == x && ((a % 10) > 0 || (b % 10) > 0) && t == dtally(a) + dtally(b))
                    f[n++] = a;
            }

            return n;
        }

        private static ulong dtally(ulong x)
        {
            ulong t = 0;
            while (x > 0)
            {
                t += 1UL << (int)((x % 10) * 6);
                x /= 10;
            }

            return t;
        }

        private static int ndigits(ulong x)
        {
            int n = 0;
            while (x > 0)
            {
                n++;
                x /= 10;
            }
            return n;
        }
    }
}