题解 | 牛牛的数学作业

#include<bits/stdc++.h>
using namespace std;
int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    
    int T;
    cin >> T;
    
    cout << fixed << setprecision(3);
    
    while (T--) {
        int n;
        cin >> n;
        
        vector<long long> nums(n);
        long long min_val = numeric_limits<long long>::max();
        long long max_val = numeric_limits<long long>::min();
        long long sum = 0;
        
        // 读取数据并计算最小值、最大值和总和
        for (int i = 0; i < n; i++) {
            cin >> nums[i];
            sum += nums[i];
            min_val = min(min_val, nums[i]);
            max_val = max(max_val, nums[i]);
        }
        
        // 计算极差
        long long range = max_val - min_val;
        
        // 计算平均值（使用double提高精度）
        double avg = static_cast<double>(sum) / n;
        
        // 计算方差
        double variance = 0.0;
        for (int i = 0; i < n; i++) {
            double diff = static_cast<double>(nums[i]) - avg;
            variance += diff * diff;
        }
        variance /= n;
        
        cout << range << " " << variance << "\n";
    }
    
    return 0;
}