uva 10555

題目連結：uva 10555 - Dead Fraction

題目大意：給出一個小數，從...開始可以是任何數字，但是保證是無限迴圈小數，將該小數用分式的形式表示，並且要求分母盡量大。

解題思路：這題主要是怎麼將無限迴圈小數轉換成分式，這樣的：

• 有小數0.abcdEEE，未迴圈部分長4，迴圈節為E，E的長度為i(假設)
• abcd+E999…(i位9）10i

#include <cstdio>#include <cstring>#include <algorithm>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;}