7-104 3101 平均年龄

#include <algorithm>
#include <cstdint>
#include <iomanip>
#include <iostream>
#include <limits>
#include <numeric>
#include <string>
#include <unordered_map>
#include <utility>
#include <vector>

using i32 = std::int32_t;
using i64 = std::int64_t;
using u32 = std::uint32_t;
using u64 = std::uint64_t;
using pii = std::pair<i32, i32>;
using pll = std::pair<i64, i64>;
using vi = std::vector<i32>;
using vll = std::vector<i64>;
using vpii = std::vector<pii>;
using vpll = std::vector<pll>;

void solve();

int main()
{
    std::cin.tie(nullptr)->sync_with_stdio(false);
    solve();
}

void solve()
{
    i32 n;
    std::cin >> n;
    i32 sum{0};
    for (i32 i = 1; i <= n; ++i)
    {
        i32 age;
        std::cin >> age;
        sum += age;
    }
    if (sum % n == 0)
    {
        std::cout << sum / n;
        return;
    }
    std::cout << std::fixed << std::setprecision(1) << static_cast<double>(sum) / n;
}