aoc2024/day-03/internal/two/solve.go

package two

import (
	"bufio"
	"bytes"
	"io"
	"regexp"

	"github.com/onyx-and-iris/aoc2024/day-03/internal/util"

	log "github.com/sirupsen/logrus"
)

var reMulOrDoOrDont = regexp.MustCompile(`mul\((?P<first>[0-9]{1,3}),(?P<second>[0-9]{1,3})\)|do\(\)|don't\(\)`)

func Solve(data []byte) (int, error) {
	r := bytes.NewReader(data)
	sum, err := parseLines(r)
	if err != nil {
		return 0, err
	}

	return sum, nil
}

func parseLines(r io.Reader) (int, error) {
	var sum int
	var do bool = true

	scanner := bufio.NewScanner(r)
	for scanner.Scan() {
		m := reMulOrDoOrDont.FindAllString(scanner.Text(), -1)
		for _, v := range m {
			switch v {
			case "do()":
				do = true
				log.Debug("hit a do")
			case "don't()":
				do = false
				log.Debug("hit a don't")
			}

			if do {
				groups := util.GetGroups(reMulOrDoOrDont, v)
				if groups["first"] != "" && groups["second"] != "" {
					log.Debugf("%s * %s\n", groups["first"], groups["second"])
					sum += util.MustConv(groups["first"]) * util.MustConv(groups["second"])
				}
			}
		}
	}

	if err := scanner.Err(); err != nil {
		return 0, err
	}

	return sum, nil
}