You have a fraction . You need to find the first occurrence of digit c into decimal notation of the fraction after decimal point.
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.
1 2 0
2
2 3 7
-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:多组数据,
每组数据输入三个数 a,b,c
输出,a/b的第几位数是c
很水的吧,直接模拟就行了,数学上好像有证明,不会有太多位的,所以大胆写吧!
#include <stdio.h>
int main() {
int a, b, c;
while(~scanf("%d%d%d",&a,&b,&c)) {
for(int i = 1; i < 255; i++) {
a *= 10;
if(a/b == c) {
printf("%d\n",i);
break;
}
a %= b;
if(i == 254) printf("-1\n");
}
}
return 0;
}