ALGORITMO QUE CONVIERTE NÚMEROS NATURALES EN ROMANOS EN C/C++

EJERCICIO:
Desarrollar un algoritmo que convierta números naturales en romanos.


#include <stdio.h>
#include <stdlib.h>


int main()
{
int num,entero,res;

printf( "Introduce un numero  \n" );
scanf( "%i", &num );

entero = num/1000;
res = num%1000;
switch( entero )
{
case 1: printf( "M" ); break;
case 2: printf( "MM" ); break;
case 3: printf( "MMM" ); break;
}

entero = res/100;
res = res%100;
switch( entero )

{
case 1: printf( "C" ); break;
case 2: printf( "CC" ); break;
case 3: printf( "CCC" ); break;
case 4: printf( "CD" ); break;
case 5: printf( "D" ); break;
case 6: printf( "DC" ); break;
case 7: printf( "DCC" ); break;
case 8: printf( "DCCC" ); break;
case 9: printf( "CM" ); break;
case 10: printf( "M" ); break;

}

entero = res/10;
res=res%10;
switch( entero )

{
case 1: printf( "X" ); break;
case 2: printf( "XX" ); break;
case 3: printf( "XXX" ); break;
case 4: printf( "XL" ); break;
case 5: printf( "L" ); break;
case 6: printf( "LX" ); break;
case 7: printf( "LXX" ); break;
case 8: printf( "LXXX" ); break;
case 9: printf( "XC" ); break;
case 10: printf( "C" ); break;


}

switch( res )
{
case 1: printf( "I" ); break;
case 2: printf( "II" ); break;
case 3: printf( "III" ); break;
case 4: printf( "IV" ); break;
case 5: printf( "V" ); break;
case 6: printf( "VI" ); break;
case 7: printf( "VII" ); break;
case 8: printf( "VIII" ); break;
case 9: printf( "IX" ); break;
case 10: printf( "X" ); break;

}
system("pause");

}