aoc2024/day-13/internal/one/util.go

package one

import (
	"bufio"
	"io"
	"regexp"
	"strconv"

	"github.com/onyx-and-iris/aoc2024/day-13/internal/machine"
)

var (
	reButton = regexp.MustCompile(`Button (?P<identifier>[A|B]): X\+(?P<xdigit>\d+), Y\+(?P<ydigit>\d+)`)
	rePrize  = regexp.MustCompile(`Prize: X\=(?P<xdigit>\d+), Y\=(?P<ydigit>\d+)`)
)

func parseLines(r io.Reader) ([]*machine.Machine, error) {
	var matches [][]string

	scanner := bufio.NewScanner(r)
	for scanner.Scan() {
		line := scanner.Text()
		if len(line) == 0 {
			continue
		}

		var m []string
		switch line := line; {
		case reButton.MatchString(line):
			m = reButton.FindStringSubmatch(line)
		case rePrize.MatchString(line):
			m = rePrize.FindStringSubmatch(line)
		}

		matches = append(matches, m)
	}

	if err := scanner.Err(); err != nil {
		return nil, err
	}

	var machines []*machine.Machine
	for i := 0; i < len(matches); i += 3 {
		machines = append(machines, machine.New(matches[i], matches[i+1], matches[i+2]))
	}

	return machines, nil
}

func mustConv(s string) int {
	n, err := strconv.Atoi(s)
	if err != nil {
		panic(err)
	}
	return n
}