Implement a kolakoski sequence generator: OEIS:A000002

kolakoski.go

package main

import (
	"fmt"
	"strconv"
	"strings"
)

var (
	// n is the number of terms to calculate
	n int = 1000
)

func main() {
	seq := make([]int, 0, n+1) // n+1 because inst 2 could add one extra
	var ind, i, toAppend int

	seq = append(seq, 1, 2, 2)
	ind = 2 // follow third instruction next
	i += 3

	for i < n { // i also functions as the length of the array
		if seq[ind] == 1 { // add one number
			toAppend = getUniq(seq)
			if seq[len(seq)-1] == 1 {
				toAppend = 2
			} else {
				toAppend = 1
			}
			seq = append(seq, toAppend)
			i++   // we added a number
			ind++ // next instruction
		} else { // add two numbers
			toAppend = getUniq(seq)
			seq = append(seq, toAppend, toAppend)
			i += 2 // we added two numbers
			ind++
		}
	}
	seq = seq[:n]
	printFormatted(seq)
}

func getUniq(seq []int) int {
	if seq[len(seq)-1] == 1 {
		return 2
	} else {
		return 1
	}
}

func printFormatted(a []int) {
	b := make([]string, len(a))
	for i, v := range a {
		b[i] = strconv.Itoa(v)
	}
	fmt.Println(strings.Join(b, ", "))
}