結果

問題 No.144 エラトステネスのざる
ユーザー maguroguma
提出日時 2020-11-23 16:36:05
言語 Go
(1.23.4)
結果
AC  
実行時間 86 ms / 2,000 ms
コード長 6,792 bytes
コンパイル時間 14,760 ms
コンパイル使用メモリ 226,112 KB
実行使用メモリ 11,080 KB
最終ジャッジ日時 2024-07-23 17:35:41
合計ジャッジ時間 16,110 ms
ジャッジサーバーID
（参考情報） 		judge2 / judge3
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 3
other AC * 17
権限があれば一括ダウンロードができます

ソースコード

diff #
プレゼンテーションモードにする

/*
URL:
https://yukicoder.me/problems/no/144
*/
package main
import (
    "bufio"
    "errors"
    "fmt"
    "io"
    "math"
    "os"
    "strconv"
)
var (
    n int
    p float64
    cnts [1000000 + 50]int
)
func main() {
    defer stdout.Flush()
    n = readi()
    p = readf()
    cp := 1.0 - p
    for i := 2; i <= n; i++ {
        for j := i * 2; j <= n; j += i {
            cnts[j]++
        }
    }
    ans := 0.0
    for i := 2; i <= n; i++ {
        val := math.Pow(cp, float64(cnts[i]))
        ans += val
    }
    fmt.Println(ans)
}
/*******************************************************************/
/********** common constants **********/
const (
    MOD = 1000000000 + 7
    // MOD          = 998244353
    ALPH_N  = 26
    INF_I64 = math.MaxInt64
    INF_B60 = 1 << 60
    INF_I32 = math.MaxInt32
    INF_B30 = 1 << 30
    NIL     = -1
    EPS     = 1e-10
)
/********** bufio setting **********/
func init() {
    // bufio.ScanWords <---> bufio.ScanLines
    reads = newReadString(os.Stdin, bufio.ScanWords)
    stdout = bufio.NewWriter(os.Stdout)
}
// mod can calculate a right residual whether value is positive or negative.
func mod(val, m int) int {
    res := val % m
    if res < 0 {
        res += m
    }
    return res
}
// min returns the min integer among input set.
// This function needs at least 1 argument (no argument causes panic).
func min(integers ...int) int {
    m := integers[0]
    for i, integer := range integers {
        if i == 0 {
            continue
        }
        if m > integer {
            m = integer
        }
    }
    return m
}
// max returns the max integer among input set.
// This function needs at least 1 argument (no argument causes panic).
func max(integers ...int) int {
    m := integers[0]
    for i, integer := range integers {
        if i == 0 {
            continue
        }
        if m < integer {
            m = integer
        }
    }
    return m
}
// chmin accepts a pointer of integer and a target value.
// If target value is SMALLER than the first argument,
//  then the first argument will be updated by the second argument.
func chmin(updatedValue *int, target int) bool {
    if *updatedValue > target {
        *updatedValue = target
        return true
    }
    return false
}
// chmax accepts a pointer of integer and a target value.
// If target value is LARGER than the first argument,
//  then the first argument will be updated by the second argument.
func chmax(updatedValue *int, target int) bool {
    if *updatedValue < target {
        *updatedValue = target
        return true
    }
    return false
}
// sum returns multiple integers sum.
func sum(integers ...int) int {
    var s int
    s = 0
    for _, i := range integers {
        s += i
    }
    return s
}
// abs is integer version of math.Abs
func abs(a int) int {
    if a < 0 {
        return -a
    }
    return a
}
// pow is integer version of math.Pow
// pow calculate a power by Binary Power (二分累乗法(O(log e))).
func pow(a, e int) int {
    if a < 0 || e < 0 {
        panic(errors.New("[argument error]: PowInt does not accept negative integers"))
    }
    if e == 0 {
        return 1
    }
    if e%2 == 0 {
        halfE := e / 2
        half := pow(a, halfE)
        return half * half
    }
    return a * pow(a, e-1)
}
/********** FAU standard libraries **********/
//fmt.Sprintf("%b\n", 255)  // binary expression
/********** I/O usage **********/
//str := reads()
//i := readi()
//X := readis(n)
//S := readrs()
//a := readf()
//A := readfs(n)
//str := ZeroPaddingRuneSlice(num, 32)
//str := PrintIntsLine(X...)
/*********** Input ***********/
var (
    // reads returns a WORD string.
    reads  func() string
    stdout *bufio.Writer
)
func newReadString(ior io.Reader, sf bufio.SplitFunc) func() string {
    r := bufio.NewScanner(ior)
    r.Buffer(make([]byte, 1024), int(1e+9)) // for Codeforces
    r.Split(sf)
    return func() string {
        if !r.Scan() {
            panic("Scan failed")
        }
        return r.Text()
    }
}
// readi returns an integer.
func readi() int {
    return int(_readInt64())
}
func readi2() (int, int) {
    return int(_readInt64()), int(_readInt64())
}
func readi3() (int, int, int) {
    return int(_readInt64()), int(_readInt64()), int(_readInt64())
}
func readi4() (int, int, int, int) {
    return int(_readInt64()), int(_readInt64()), int(_readInt64()), int(_readInt64())
}
// readll returns as integer as int64.
func readll() int64 {
    return _readInt64()
}
func readll2() (int64, int64) {
    return _readInt64(), _readInt64()
}
func readll3() (int64, int64, int64) {
    return _readInt64(), _readInt64(), _readInt64()
}
func readll4() (int64, int64, int64, int64) {
    return _readInt64(), _readInt64(), _readInt64(), _readInt64()
}
func _readInt64() int64 {
    i, err := strconv.ParseInt(reads(), 0, 64)
    if err != nil {
        panic(err.Error())
    }
    return i
}
// readis returns an integer slice that has n integers.
func readis(n int) []int {
    b := make([]int, n)
    for i := 0; i < n; i++ {
        b[i] = readi()
    }
    return b
}
// readlls returns as int64 slice that has n integers.
func readlls(n int) []int64 {
    b := make([]int64, n)
    for i := 0; i < n; i++ {
        b[i] = readll()
    }
    return b
}
// readf returns an float64.
func readf() float64 {
    return float64(_readFloat64())
}
func _readFloat64() float64 {
    f, err := strconv.ParseFloat(reads(), 64)
    if err != nil {
        panic(err.Error())
    }
    return f
}
// ReadFloatSlice returns an float64 slice that has n float64.
func readfs(n int) []float64 {
    b := make([]float64, n)
    for i := 0; i < n; i++ {
        b[i] = readf()
    }
    return b
}
// readrs returns a rune slice.
func readrs() []rune {
    return []rune(reads())
}
/*********** Output ***********/
// PrintIntsLine returns integers string delimited by a space.
func PrintIntsLine(A ...int) string {
    res := []rune{}
    for i := 0; i < len(A); i++ {
        str := strconv.Itoa(A[i])
        res = append(res, []rune(str)...)
        if i != len(A)-1 {
            res = append(res, ' ')
        }
    }
    return string(res)
}
// PrintIntsLine returns integers string delimited by a space.
func PrintInts64Line(A ...int64) string {
    res := []rune{}
    for i := 0; i < len(A); i++ {
        str := strconv.FormatInt(A[i], 10) // 64bit int version
        res = append(res, []rune(str)...)
        if i != len(A)-1 {
            res = append(res, ' ')
        }
    }
    return string(res)
}
// Printf is function for output strings to buffered os.Stdout.
// You may have to call stdout.Flush() finally.
func printf(format string, a ...interface{}) {
    fmt.Fprintf(stdout, format, a...)
}
/*********** Debugging ***********/
// debugf is wrapper of fmt.Fprintf(os.Stderr, format, a...)
func debugf(format string, a ...interface{}) {
    fmt.Fprintf(os.Stderr, format, a...)
}
// ZeroPaddingRuneSlice returns binary expressions of integer n with zero padding.
// For debugging use.
func ZeroPaddingRuneSlice(n, digitsNum int) []rune {
    sn := fmt.Sprintf("%b", n)
    residualLength := digitsNum - len(sn)
    if residualLength <= 0 {
        return []rune(sn)
    }
    zeros := make([]rune, residualLength)
    for i := 0; i < len(zeros); i++ {
        zeros[i] = '0'
    }
    res := []rune{}
    res = append(res, zeros...)
    res = append(res, []rune(sn)...)
    return res
}
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