题目链接：uva 10555 - Dead Fraction

题目大意：给出一个小数，从...开始可以是任何数字，但是保证是无限循环小数，将该小数用分式的形式表示，并且要求分母尽量大。

解题思路：这题主要是怎么将无限循环小数转换成分式，这样的：

• 有小数0.abcdEEE，未循环部分长4，循环节为E，E的长度为i(假设)
• abcd+E999…(i位9）10i

  #include 
       
         #include 
        
          #include 
         
           using namespace std; typedef long long ll; const int maxn = 105; const ll INF = 0x3f3f3f3f3f3f3f; char s[maxn]; ll gcd (ll a, ll b) { return b ? gcd(b, a%b) : a; } int main () { while (scanf("%s", s) == 1 && strcmp(s, "0")) { int len = strlen(s)-5; ll ansu, ansd = INF; for (int i = 0; i < len; i++) s[i] = s[i+2]; for (int i = 0; i < len; i++) { ll d = 1, u = 0; for (int j = 0; j < i; j++) { d = d * 10; u = u * 10 + s[j] - '0'; } ll x = 0, y = 0; for (int j = i; j < len; j++) { x = x * 10 + s[j] - '0'; y = y * 10 + 9; } d = d * y; u = u * y + x; ll g = gcd(d, u); u /= g; d /= g; if (d < ansd) { ansd = d; ansu = u; } } printf("%lld/%lld\n", ansu, ansd); } return 0; }