poj1930 Dead Fraction

思路：

循环小数化分数，枚举所有可能的循环节，取分母最小的那个。

实现：

 #include <iostream>
 #include <cstdio>
 #include <string>
 using namespace std;

 const int INF = 0x3f3f3f3f;

 int gcd(int a, int b)
 {
     return !b ? a : gcd(b, a % b);
 }

 int lcm(int a, int b)
 {
     return a / gcd(a, b) * b;
 }

 int toNum(string s)
 {
     int n = s.length();
     int res = ;
     for (int i = ; i < n; i++)
     {
         res += s[i] - '';
         if (i != n - )
             res *= ;
     }
     return res;
 }

 int main()
 {
     string s;
     while (cin >> s, s != "")
     {
         s = s.substr(, s.length() - );
         int n = s.length();
         int minn = INF;
         int minm = ;
         for (int i = ; i < n; i++)
         {
             int x = toNum(s.substr(i, n - i));
             int y = ;
             for (int j = ; j < n - i - ; j++)
             {
                 y *= ;
                 y += ;
             }
             for (int j = ; j < i; j++)
             {
                 y *= ;
             }
             int p = toNum(s.substr(, i));
             int q = ;
             for (int j = ; j < i; j++)
             {
                 q *= ;
             }
             int l = lcm(y, q);
             int tmp = l / y * x + l / q * p;
             int g = gcd(tmp, l);
             tmp /= g;
             l /= g;
             if (l < minn)
             {
                 minn = l;
                 minm = tmp;
             }
         }
         cout << minm << "/" << minn << endl;
     }
     return ;
 }