Generator of AB strings

const.go

package main

const (
	letterA = "a"
	letterB = "b"
)

main.go

package main

import (
	"fmt"
	"os"
	"strconv"
)

func main() {
	if len(os.Args) != 3 {
		fmt.Fprintf(os.Stderr, "Usage: %s number_of_As number_of_Bs\n", os.Args[0])
		os.Exit(1)
	}

	// Input arguments
	numberOfAs, _ := strconv.ParseInt(os.Args[1], 10, 32)
	numberOfBs, _ := strconv.ParseInt(os.Args[2], 10, 32)
	word, err := GenerateString(int(numberOfAs), int(numberOfBs))

	if err != nil {
		println(err.Error())
		return
	}

	println(word)
}

math.go

package main

func minInt(a, b int) int {
	if a < b {
		return a
	}

	return b
}

strings.go

package main

import (
	"github.com/pkg/errors"
	"strings"
)

func GenerateString(numberOfAs, numberOfBs int) (string, error) {
	char1 := letterA
	char2 := letterB
	max := numberOfAs
	min := numberOfBs
	generateWord := ""

	if numberOfBs > numberOfAs {
		char1 = letterB
		char2 = letterA
		max = numberOfBs
		min = numberOfAs
	}

	if max > (2*min)+2 {
		return "", errors.New("Wrong numbers")
	}

	x := minInt(max-min, min)
	y := min - x
	z := 0

	if max > (2 * min) {
		z = max - 2*min
	}

	// generateWord = AAB^x + AB^y + A^z
	generateWord += strings.Repeat(char1+char1+char2, x)
	generateWord += strings.Repeat(char1+char2, y)
	generateWord += strings.Repeat(char1, z)

	return generateWord, nil
}

Having in input two numbers "number of As" and "number of Bs", the goal is to generate a string containing the requested number A and B. The only constraint is that the generate word can not have a letter 3 times in a row.

Valid word
abaa

Not valid word
aaab