题解 | 牛牛的数学作业

package main

import (
	"bufio"
	"fmt"
	"os"
	"sort"
	"strconv"
	"strings"
)

func main() {
	sc := bufio.NewScanner(os.Stdin)
	sc.Scan()
	n, _ := strconv.Atoi(sc.Text())

	for i := 0; i < n; i++ {
		sc.Scan()
		n1, _ := strconv.Atoi(sc.Text())
		sc.Scan()
		a1 := make([]int, n1)
		sum := 0.0
		for i := 0; i < n1; i++ {
			a1[i], _ = strconv.Atoi(strings.Fields(sc.Text())[i])
			sum += float64(a1[i])
		}
		sort.Ints(a1)
		a := sum / float64(n1)
		f := 0.0
		for i := 0; i < n1; i++ {
			f += (float64(a1[i]) - a) * (float64(a1[i]) - a)
		}
		fmt.Printf("%d %.3f\n", a1[n1-1]-a1[0], f/float64(n1))
	}
}