Arvonta

#include <bits/stdc++.h>

double pow(double x, int exp) {
    double res = 1.0;
    while (exp) {
        if (exp & 1) res *= x;
        x *= x;
        exp >>= 1;
    }
    return res;
}

int main() {
    int t;
    std::cin >> t;
    for (int i = 0, n; i < t; ++i) {
        std::cin >> n;
        std::cout << std::fixed << std::setprecision(7)
                  << (1.0 - pow(1.0 - 1.0 / n, n)) << '\n';
    }
}

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 2

Verdict: ACCEPTED