Demo algorithm to get the random choice with different weight.

random_with_weight.go

package main

import (
	"fmt"
	"math/rand"
)

func randomWithWeight(weights []int) int {
	var sum int
	for _, v := range weights {
		sum += v
	}

	rnd := rand.Intn(sum)
	for i := 0; i < len(weights); i++ {
		if rnd < weights[i] {
			return i
		}
		rnd -= weights[i]
	}
	return 0
}

func main() {
	rand.Seed(64168918564)
	// 4 Choice
	weightOfChoice := []int{59, 1, 10, 30}

	var freqs [4]int
	// Loop 10,000 times
	for i := 0; i < 100000; i++ {
		freqs[randomWithWeight(weightOfChoice)] += 1
	}

	// Show the frequency of each choice.
	for _, v := range freqs {
		fmt.Println(v)
	}
}