题解 | 牛牛的数学作业

#include <iostream>
#include <vector>
#include <iomanip>
#include <cmath>

using namespace std;

int main() {
    int T; // 试卷数量
    cin >> T;
    
    // 处理每张试卷
    for(int i = 0; i < T; i++) {
        int n; // 本试卷上的数字个数
        cin >> n;
        
        vector<int> numbers(n);
        
        for(int j = 0; j < n; j++) {
            cin >> numbers[j];
        }
        
        int max_val = numbers[0];
        int min_val = numbers[0];
        
        for(int j = 1; j < n; j++) {
            if(numbers[j] > max_val) {
                max_val = numbers[j];
            }
            if(numbers[j] < min_val) {
                min_val = numbers[j];
            }
        }
        
        int range = max_val - min_val; // 极差
        
        long long sum = 0; 
        for(int num : numbers) {
            sum += num;
        }
        
        double mean = static_cast<double>(sum) / n;
        
        double variance = 0.0;
        for(int num : numbers) {
            variance += pow(num - mean, 2);
        }
        variance /= n; // 方差
        cout << range << " " << fixed << setprecision(3) << variance << endl;
    }
}
// 64 位输出请用 printf("%lld")