#include <iostream>
#include <fstream>
using namespace std;
int cifControl(int n)
{
while (n>9)
{
unsigned long int s=0;
while (n>0)
{
s+=n%10;
n/=10;
}
n=s;
return n;
}
}
int main()
{
ifstream in("control1.in");
ofstream out("control1.out");
unsigned long int a, b, i;
unsigned short int c, k=0;
in >> a >> b >> c;
for (i=a; i<=b; i++)
if (cifControl(i)==c) k++;
out << k;
in.close();
out.close();
return 0;
}
PROGRAM EFICIENT PENTRU CALCULAREA CIFREI DE CONTROL.
Aceasta e varianta recomandata pentru un timp de executie mic :
#include <iostream>
using namespace std();
int main(){
int n;
cin >> n;
if(n==0) cout << 0;
else if (n%9==0) cout << 9;
else cout << n%9;
}
