HDU 1099 Lottery

看英语不是太懂，最后看了它们的解题思路。

#include <iostream>
using namespace std;

typedef long long ll;

ll gcd(ll a, ll b) {
    if (b == 0) return a;
    gcd(b, a%b);
}

int digits(ll a) {
    int cnt = 0;
    while (a > 9 || a % 10 != 0) {
        cnt++;
        a = a / 10;
    }
    return cnt;
}

ll fenmu(int n) {
    ll sum = 1;
    for (int i = 1; i <= n; i++)
        sum = sum*i/gcd(sum, i);
    return sum;
}

ll fenzi(int n) {
    ll tmp = fenmu(n);
    ll sum = 0;
    for (int i = 1; i <= n; i++)
        sum = sum+tmp / i;
    return n*sum;
}

int main() {
    int n;
    while (cin >> n) {
        ll fm = fenmu(n);
        ll fz = fenzi(n);
        ll zs = fz / fm;
        fz %= fm;
        if (fz%fm == 0) {
            cout << zs << endl;
            continue;
        }
            
        int ws = digits(zs);
        for (int i = 0; i <= ws; i++)
            cout << " ";

        
        int tmp = gcd(fz, fm);
        while (tmp!= 1) {
            fz /= tmp;
            fm /= tmp;
            tmp = gcd(fz, fm);
        }
        cout << fz << endl;

        cout << zs << " ";
        ws = digits(fm);
        for (int i = 0; i < ws; i++)
            cout << "-";
        cout << endl;

         ws = digits(zs);
        
        for (int i = 0; i <= ws; i++)
            cout << " ";
        cout << fm << endl;
    }
}