package main import ( "bufio" "fmt" "os" "sort" "strconv" ) func out(x ...interface{}) { fmt.Println(x...) } var sc = bufio.NewScanner(os.Stdin) func getInt() int { sc.Scan() i, e := strconv.Atoi(sc.Text()) if e != nil { panic(e) } return i } func getInts(N int) []int { ret := make([]int, N) for i := 0; i < N; i++ { ret[i] = getInt() } return ret } func getString() string { sc.Scan() return sc.Text() } // min, max, asub, absなど基本関数 func max(a, b int) int { if a > b { return a } return b } func min(a, b int) int { if a < b { return a } return b } func asub(a, b int) int { if a > b { return a - b } return b - a } func abs(a int) int { if a >= 0 { return a } return -a } func lowerBound(a []int, x int) int { idx := sort.Search(len(a), func(i int) bool { return a[i] >= x }) return idx } func upperBound(a []int, x int) int { idx := sort.Search(len(a), func(i int) bool { return a[i] > x }) return idx } // NextPermutation generates the next permutation of the // sortable collection x in lexical order. It returns false // if the permutations are exhausted. // // Knuth, Donald (2011), "Section 7.2.1.2: Generating All Permutations", // The Art of Computer Programming, volume 4A. // ※NextPermutationは辞書順で次を返す func NextPermutation(x sort.Interface) bool { n := x.Len() - 1 if n < 1 { return false } j := n - 1 for ; !x.Less(j, j+1); j-- { if j == 0 { return false } } l := n for !x.Less(j, l) { l-- } x.Swap(j, l) for k, l := j+1, n; k < l; { x.Swap(k, l) k++ l-- } return true } func main() { sc.Split(bufio.ScanWords) N := getInt() a := getInts(N) b := getInts(N) n := make([]int, N) for i := 0; i < N; i++ { n[i] = i } tot := 0 cnt := 0 for { win := 0 lose := 0 for i := 0; i < N; i++ { if a[n[i]] > b[i] { win++ } else if a[n[i]] < b[i] { lose++ } } if win > lose { cnt++ } tot++ if !NextPermutation(sort.IntSlice(n)) { break } } out(float64(cnt) / float64(tot)) }