8 queens puzzle in Go

queens.go

package main

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

type Queens []int

func (queens Queens) Choices() []int {
	currentLayer := len(queens)
	result := [8]int{}
	for i := 0; i < 8; i++ {
		result[i] = i
	}
	for i, c := range queens {
		result[c] = -1
		a := c + currentLayer - i
		if a >= 0 && a < 8 {
			result[a] = -1
		}
		b := c - currentLayer + i
		if b >= 0 && b < 8 {
			result[b] = -1
		}
	}
	final := []int{}
	for _, r := range result {
		if r != -1 {
			final = append(final, r)
		}
	}
	return final
}

// Iter to next layer
func Iter(queenList []Queens) []Queens {
	final := []Queens{}
	for _, queens := range queenList {
		for _, c := range queens.Choices() {
			q := make([]int, len(queens))
			copy(q, queens)
			final = append(final, append(q, c))
		}
	}
	return final
}

func main() {
	queensList := []Queens{[]int{}}

	for i := 0; i < 8; i++ {
		queensList = Iter(queensList)
	}
	fmt.Printf("Total: %d\n", len(queensList))
	fmt.Printf("%v\n", queensList)

	r := rand.New(rand.NewSource(time.Now().UnixNano()))
	queens := queensList[r.Intn(len(queensList))]
	buf := new(bytes.Buffer)
	strings := "oooooooo"
	for _, q := range queens {
		buf.WriteString(strings[0:q])
		buf.WriteString("x")
		buf.WriteString(strings[q:])
		buf.WriteString("\n")
	}
	buf.WriteTo(os.Stdout)
}