counter.go

package main

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

func main() {

	nums := make([]uint16, 10000)

	for i, _ := range nums {
		nums[i] = uint16(rand.Uint32())
	}

	slowcount := map[uint16]int{}
	fastcount := make([]int, int(math.Pow(2, 16)))

	start := time.Now()
	for _, n := range nums {
		//printBits(n)
		if count, ok := slowcount[n]; ok {
			slowcount[n] = count + 1
		} else {
			slowcount[n] = 1
		}
	}
	fmt.Printf("slowcount: %d\n", time.Now().UnixNano()-start.UnixNano())

	start = time.Now()
	for _, n := range nums {
		fastcount[n]++
	}
	fmt.Printf("fastcount: %d\n", time.Now().UnixNano()-start.UnixNano())

	for i, _ := range fastcount {
		if fastcount[i] != slowcount[uint16(i)] {
			fmt.Printf("WRONT COUNT\n")
		}
	}
	fmt.Printf("done\n")
}

func printBits(n int16) {

	for i := int16(128); i > 0; i >>= 1 {
		if i&n == i {
			fmt.Print(1)
		} else {
			fmt.Print(0)
		}
	}

	fmt.Println()
}