aoc2023/day-2/one.go

package main

import (
	"regexp"
	"strconv"
	"strings"
)

var regex = map[string]*regexp.Regexp{
	"red":   regexp.MustCompile(`(?P<red>\d+) red`),
	"green": regexp.MustCompile(`(?P<green>\d+) green`),
	"blue":  regexp.MustCompile(`(?P<blue>\d+) blue`),
	"game":  regexp.MustCompile(`Game (?P<game>\d+)`),
}

var limits = map[string]int{
	"red":   12,
	"green": 13,
	"blue":  14,
}

// isValidGame calculates if a game was possible based on the limits of each cube colour
func isValidGame(data string) (bool, error) {
	for _, colour := range []string{"red", "green", "blue"} {
		m := regex[colour].FindAllStringSubmatch(data, -1)
		for _, s := range m {
			n, err := strconv.Atoi(s[1])
			if err != nil {
				return false, err
			}
			if n > limits[colour] {
				return false, nil
			}
		}
	}

	return true, nil
}

// one returns the sum of ids for all games that were possible
func one(lines []string) (int, error) {
	sum := 0

	for _, line := range lines {
		identifier, data := func() (string, string) {
			x := strings.Split(line, ":")
			return x[0], x[1]
		}()

		isValidGame, err := isValidGame(data)
		if err != nil {
			return 0, err
		}
		if isValidGame {
			id, err := getIdForGame(identifier)
			if err != nil {
				return 0, err
			}
			sum += id
		}
	}

	return sum, nil
}