aoc2024/day-05/internal/util/util.go

package util

import (
	"bufio"
	"io"
	"log"
	"strconv"
	"strings"
)

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

func ParseLines(r io.Reader) ([][][]int, error) {
	data := make([][][]int, 2)

	filter := func(r rune) bool {
		return r == '|' || r == ','
	}

	buf, err := io.ReadAll(r)
	if err != nil {
		log.Fatal(err)
	}
	parts := strings.Split(string(buf), "\n\n")

	for i, part := range parts {
		scanner := bufio.NewScanner(strings.NewReader(part))
		for scanner.Scan() {
			filtered := strings.FieldsFunc(scanner.Text(), filter)
			var nums []int
			for _, n := range filtered {
				nums = append(nums, MustConv(n))
			}
			data[i] = append(data[i], nums)
		}

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

	return data, nil
}