Submission #6905279

---

Source Code Expand

package main

import (
	"fmt"
)

func main() {
	var n int
	fmt.Scan(&n)
	c := make([]int, n)
	for i := 0; i < n; i++ {
		fmt.Scan(&c[i])
	}
	p := 1
	for i := 1; i <= n; i++ {
		p *= i
	}

	l := len(c)
	cnt := 0
	for i := 0; i < p; i++ {
		c = nextPermutation(c)
		b := make([]bool, len(c))
		for j := 0; j < l-1; j++ {
			for k := j + 1; k < l; k++ {
				if c[k]%c[j] == 0 {
					b[k] = toggle(b[k])
				}
			}
		}
		cnt += count(b)
	}
	fmt.Println(float64(cnt) / float64(p))
}

func toggle(b bool) bool {
	if b {
		return false
	}
	return true
}

func count(bs []bool) int {
	cnt := 0
	for _, v := range bs {
		if !v {
			cnt++
		}
	}
	return cnt
}

func nextPermutation(ints []int) []int {
	var j int
	k := -1
	for i := len(ints) - 1; i >= 1; i-- {
		if ints[i] > ints[i-1] {
			k = i - 1
			break
		}
	}
	if k == -1 {
		for i := 0; i < len(ints)/2; i++ {
			ints[i], ints[len(ints)-i-1] = ints[len(ints)-i-1], ints[i]
		}
		return ints
	}
	for i := len(ints) - 1; i > k; i-- {
		if ints[i] > ints[k] {
			j = i
			break
		}
	}
	ints[k], ints[j] = ints[j], ints[k]
	for i := 1; i <= (len(ints)-k)/2; i++ {
		ints[k+i], ints[len(ints)-i] = ints[len(ints)-i], ints[k+i]
	}
	return ints
}

Submission Info

Judge Result