Shows the distribution of indgree using random picking

random_indgree_distribution.go

package main

import (
	"crypto/rand"
	"fmt"
	"math/big"
	"sync"
)

type member struct {
	sync.Mutex
	array []int
}

func main() {
	wg := new(sync.WaitGroup)
	n := 10000
	fan := 5
	wg.Add(n)
	m := &member{array: make([]int, n)}
	for i := 0; i < n; i++ {
		go func() {
			for j := 0; j < fan; j++ {
				index, err := rand.Int(rand.Reader, big.NewInt(int64(n)))
				if err != nil {
					panic(err)
				}
				m.Lock()
				m.array[int(index.Int64())]++
				m.Unlock()
			}
			wg.Done()
		}()
	}
	wg.Wait()

	cnt := make([]int, n)
	for i := 0; i < n; i++ {
		cnt[m.array[i]]++
	}
	for i := 0; i < 50; i++ {
		fmt.Println(i, ": ", cnt[i])
	}
}