Generate bit strings

bit_strings.go

package main

import "fmt"

// BitStrings generates all combinations of binary values, as strings, having
// the specified number of bits.
func BitStrings(n int) []string {
	if n <= 0 {
		return nil
	}

	rdCap := 1 << (n - 1)
	wrCap := 1 << n
	if n&1 == 1 {
		rdCap, wrCap = wrCap, rdCap
	}
	rd := make([]string, 0, rdCap)
	wr := make([]string, 1, wrCap)

	for range n {
		rd, wr = wr, rd[:0]
		for _, s := range rd {
			wr = append(wr, s+"0", s+"1")
		}
	}
	return wr
}

func main() {
	fmt.Println("BitStrings(1):", BitStrings(1))
	fmt.Println("BitStrings(2):", BitStrings(2))
	fmt.Println("BitStrings(3):", BitStrings(3))
}

// https://go.dev/play/p/dyWHTTj8wNe