OJ Board

If you can change your approaches to input the card number, then the problem become easy. Try the following code segment for inputing card number:

int credit[16], j;

for(j=0;j<16;j++)
{
scanf("%1d", &credit[j]);
}

Then sum the number in odd index of the array credit[] (i.e. at 1, 3, 5 ...

A better approach to solve this problem should be using prime divisor. If you can find that a number N = (a^x)*(b^y)*(c^z) where a, b, c are prime number then the number of divisor of N should be (x+1)*(y+1)*(Z+1).

If you have already solve 583 (prime factor) then it will be easier for you to ...