randomized.go

package main

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

type weight struct {
	weight    float64
	threshold float64
	count     int
}

func main() {
	lists := []*weight{&weight{weight: 1.0}, &weight{weight: 3.0}, &weight{weight: 5.0}, &weight{weight: 1.0}}

	totalW := 0.0
	for _, v := range lists {
		(*v).threshold = totalW
		totalW += v.weight
	}

	rand.Seed(time.Now().UnixNano())
	for n := 0; n < 100000000; n++ {
		rTotalW := rand.Float64() * totalW
		for i := len(lists) - 1; i >= 0; i-- {
			if lists[i].threshold <= rTotalW {
				lists[i].count++
				break
			}
		}
	}

	for k, v := range lists {
		fmt.Printf("%d: %.2f %d\n", k, v.weight, v.count)
	}
}