POJ2551 Ones

简单暴力会超时，稍微动脑筋优化一下即可

其实根据(a+b)%d=(a%d+b%d)%d就可以做出来了。

以7为例

1%7=1              1%7=1

11%7=4          （10%7+1）%7=4

111%7=6        （4*10%7+1）%7=6

1111%7=5      （6*10%7+1）%7=5

11111%7=2     （5*10%7+1）%7=2

111111%7=0   （2*10%7+1）%7=0

输出6.

 

Ones

Time Limit: 1000MS		Memory Limit: 65536K
Total Submissions: 10892		Accepted: 6193

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

Source

Waterloo local 2001.06.02

 

//oimonster
#include<cstdio>
#include<cstdlib>
#include<iostream>
using namespace std;
int main(){
    int i,j,n;
    bool f;
    int s,t=0;
    while(scanf("%d",&n)!=EOF){
        f=false;
        t=s=1;
        t=t%n;
        while(t!=0){
            t=(t*10%n+1)%n;
            s++;
        }
        printf("%d
",s);
    }
    return 0;
}