学习到了辗转相减法(更相减损术)
可以用来求指数类型的最大公约数 ，分子分母分别求
最终可以得到N次方根的最简形式

#include<bits/stdc++.h>
using namespace std;
const int N = 110;
typedef long long LL;
LL a[N],b[N],c[N];
int n;

LL gcd(LL a, LL b) {
    if (b) {
        gcd(b, a % b);
    }
    else return a;
}
LL gcd_sub(LL a, LL b) {
    if (a < b)
        swap(a, b);
    if (b == 1)return a;
    else gcd_sub(b, a / b);
}
int main()
{
    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }
    sort(a, a + n);
    int cnt = 0;
    for (int i = 1; i < n; i++) {
        if (a[i] != a[i - 1]) {
            LL d = gcd(a[i], a[0]);
            b[cnt] = a[i] / d;
            c[cnt] = a[0] / d;
            cnt++;
        }
    }
    LL up = b[0], down = c[0];
    for (int i = 1; i < cnt; i++) {
        up = gcd_sub(up, b[i]);
        down = gcd_sub(down, c[i]);
    }

    cout << up << '/' << down << endl;
    return 0;
}