Numbers ending in 3 have at least one multiple having all ones

Question

Hi Here is a Q that was asked in Adobe Interview.

Numbers ending in 3 have at least one multiple having all ones. for eg., 3 and 13 have amultiples like 111 and 111111 respectively. Given such a no. , find the smallest such multiple of that number. The multiple can exceed the range of int, long. You cannot use any complex data structure.

Can you provide me with an efficient solution

Answer 1

got the answer now :)

int count=1, rem=1; 
while(rem)
{
 rem= (rem*10+1)%n; count++;
} 
 while(count--){ cout<<"1";}