optimized version of isogram for golang

benchmark_isogram_optimized.go

package main

// Run the following command
// $ time go run main.go

// Golang Benchmark
// real	0m8.102s
// user	0m1.004s
// sys	0m0.504s

// Python Benchmark
// real	0m0.782s
// user	0m0.617s
// sys	0m0.099s

import (
	"bufio"
	"fmt"
	"io"
	"log"
	"os"
	"runtime"
	"strings"
	"sync"
	"sync/atomic"
)

// Before
// real	0m1.124s
// user	0m0.971s
// sys	0m0.159s

// After
// real	0m0.442s
// user	0m1.017s
// sys	0m0.084s

func main() {
	f, err := os.Open("/usr/share/dict/words")
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()

	reader, writer := io.Pipe()
	wordC := make(chan string, 1024)

	var wg sync.WaitGroup
	var total uint64 = 0
	wg.Add(runtime.NumCPU())
	for i := 0; i < runtime.NumCPU(); i++ {
		go func() {
			var count uint64 = 0
			for word := range wordC {
				if IsIsogram(word) {
					count += 1
				}
			}
			atomic.AddUint64(&total, count)
			wg.Done()
		}()
	}

	go func() {
		scanner := bufio.NewScanner(reader)
		for scanner.Scan() {
			wordC <- scanner.Text()
		}
		close(wordC)
	}()

	go func() {
		_, err := io.Copy(writer, f)
		if err != nil {
			log.Fatal(err)
		}
		writer.Close()
	}()
	wg.Wait()

	fmt.Printf("%d isograms found!", total)
}

func IsIsogram(s string) bool {
	if s == "" {
		return false
	}
	// Create a map to store the unique characters
	d := make(map[rune]int)
	for _, r := range strings.ToLower(s) {
		// Set unique characters
		d[r] += 1
	}
	// Now we have a map of the unique characters
	// In order to get an Array of the keys, we loop
	var o []string

	for k, _ := range d {
		o = append(o, string(k))
	}
	// Array `o` now contains the unique strings
	// Check how many times the strings are repeated
	repeat := int(len(s) / len(o))

	// Now check if each unique characters have the same amount
	for _, v := range d {
		if v != repeat {
			return false
		}
	}

	return true
}