poj-2551-ones
Description
Given any integer 0 <= n <= 10000 not divisible by 2 or 5, some multiple of n is a number which in decimal notation is a sequence of 1's. How many digits are in the smallest such a multiple of n?
Input
Each line contains a number n.
Output
Output the number of digits.
Sample Input
3 7 9901
Sample Output
3 6 12
题目大意:
输入n,求出不能整除3和5,却能整除d并且这个数各位都是1;
111111111111%9901==0;
#include <iostream> #include <cstdio> using namespace std; int main() { int n; while(~scanf("%d",&n))//EOF { int cnt=1; int num=1; while(num%n) { num=(num*10+1)%n;//直接找由1构成的数,判断是不是n的倍数 cnt++; } printf("%d\n",cnt); } return 0; }