You have a fraction . You need to find the first occurrence of digit c into decimal notation of the fraction after decimal point.
Input
The first contains three single positive integers a, b, c (1 ≤ a < b ≤ 105, 0 ≤ c ≤ 9).
Print position of the first occurrence of digit c into the fraction. Positions are numbered from 1 after decimal point. It there is no such position, print -1.
Examples
Input
1 2 0
Output
2
Input
2 3 7
Output
-1
The fraction in the first example has the following decimal notation: . The first zero stands on second position.
The fraction in the second example has the following decimal notation: . There is no digit 7 in decimal notation of the fraction.
题意:求a/b的小数部分中第几位是c思路:模拟除法,现将a,b约分,减少运算次数
代码:
#include<bits/stdc++.h> using namespace std; const int N = 1e5; int gcd(int a,int b){ while(b){ int c=a%b; a=b; b=c; } return a; } int main(){ int n,m,c; cin>>n>>m>>c; int temp=gcd(n,m); n/=temp; m/=temp; int ans=-1; for(int i=1;i<=N;i++){ n*=10; if(n/m==c){ ans=i; break; } n%=m; } cout<<ans<<endl; return 0; }