codewars/go/kyu7/the_baum_sweet_sequence/k.go

package kata

import (
	"fmt"
)

type state byte

/*
The sequence is documented as only being tested for up to 1E6, i.e. 24 bits.

It is assumed to ignore leading zeroes.

A faster solution might use the 2-automaton mechanism described in
https://www.emis.de//journals/SLC/opapers/s30allouche.pdf
*/
func BaumSweet(ch chan<- int) {
	// Handle n == 0 as binary empty string, par kata discussion.
	ch <- 1
N_LOOP:
	for n := 1; n < 1E4+1; n++ {
		// Adding external 1s does not changes the result, and ensures the potential
		// final 0 sequence is measured without a special case.
		s := []byte(fmt.Sprintf("1%b1", n))
		// Runes will be '0' and '1' by construction, so always single-byte.
		segmentLength := 0
		for i := 0; i < len(s); i++ {
			if s[i] == '1' {
				if segmentLength%2 == 1 {
					ch <- 0
					continue N_LOOP
				} else {
					// Do nothing
				}
			} else {
				segmentLength++
			}
		}
		ch <- 1
	}
}