[Go]重み付き乱択アルゴリズムを整数だけで完結させる ref: https://qiita.com/cia_rana/items/dca5b008fcee67adda50

file0.go

weights := []int{1, 2, 3, 4, 5, 6, 7, 8, 9}

file1.go

boundaries := make([]int, len(weights)+1)
for i := 1; i < len(boundaries); i++ {
    boundaries[i] = boundaries[i-1] + weights[i-1]
}

file2.go

x := rand.Intn(boundaryLast) + 1

file3.go

idx := sort.SearchInts(boundaries, x)

file4.go

package main

import (
    "fmt"
    "math/rand"
    "sort"
    "time"
)

const N = 1000000

func main() {
    rand.Seed(time.Now().UnixNano())

    weights := []int{1, 2, 3, 4, 5, 6, 7, 8, 9}

    boundaries := make([]int, len(weights)+1)
    for i := 1; i < len(boundaries); i++ {
        boundaries[i] = boundaries[i-1] + weights[i-1]
    }

    boundaryLast := boundaries[len(boundaries)-1]
    counter := make([]int, len(weights))
    for i := 0; i < N; i++ {
        x := rand.Intn(boundaryLast) + 1
        idx := sort.SearchInts(boundaries, x) - 1
        counter[idx]++
    }

    fmt.Println("|weight|expected|actual|")
    fmt.Println("|:-:|:-:|:-:|")
    for i := 0; i < len(weights); i++ {
        fmt.Printf(
            "|%d|%f|%f|\n",
            weights[i],
            float64(weights[i])/float64(boundaryLast),
            float64(counter[i])/float64(N),
        )
    }
}

file5.go

package main

import (
    "fmt"
    "math/rand"
    "sort"
    "time"
)

const N = 1000000

func main() {
    rand.Seed(time.Now().UnixNano())

    waits := []int{1, 2, 3, 4, 5, 6, 7, 8, 9}

    boundaries := make([]int, len(waits)+1)
    for i := 1; i < len(boundaries); i++ {
        boundaries[i] = boundaries[i-1] + waits[i-1]
    }

    boundaryLast := boundaries[len(boundaries)-1]
    counter := make([]int, len(waits))
    for i := 0; i < N; i++ {
        x := rand.Intn(boundaryLast)+1
        idx := sort.SearchInts(boundaries, x) - 1
        counter[idx]++
    }

    fmt.Println("|wait|expected|actual|")
    fmt.Println("|:-:|:-:|:-:|")
    for i := 0; i < len(waits); i++ {
        fmt.Printf("|%d|%f|%f|\n", waits[i], float64(waits[i]) / float64(boundaryLast), float64(counter[i]) / float64(N))
    }
}