adventofcode2023/day02.go

package main

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

var replacer = strings.NewReplacer(",", " ", ";", " ")

func maxgame(r io.Reader) (red, green, blue int) {
	scanner := bufio.NewScanner(r)
	scanner.Split(bufio.ScanWords)

	for {
		if !scanner.Scan() {
			break
		}

		n, _ := strconv.Atoi(scanner.Text())

		scanner.Scan()
		switch scanner.Text() {
		case "red":
			if n > red {
				red = n
			}
		case "green":
			if n > green {
				green = n
			}
		case "blue":
			if n > blue {
				blue = n
			}
		}

	}
	return
}

type day02 struct{}

func (d day02) solve1(r io.Reader) string {
	var (
		totalred   = 12
		totalgreen = 13
		totalblue  = 14
		gameSum    = 0
		scanner    = bufio.NewScanner(r)
	)

	for gameN := 1; scanner.Scan(); gameN++ {
		line := scanner.Text()
		_, game, _ := strings.Cut(line, ": ")
		sr := strings.NewReader(replacer.Replace(game))
		red, green, blue := maxgame(sr)
		if red < totalred && green < totalgreen && blue < totalblue {
			gameSum += gameN
		}
	}

	return fmt.Sprintf("%d", gameSum)
}

func (d day02) solve2(r io.Reader) string {
	var (
		sum     = 0
		scanner = bufio.NewScanner(r)
	)

	for scanner.Scan() {
		line := scanner.Text()
		_, game, _ := strings.Cut(line, ": ")
		sr := strings.NewReader(replacer.Replace(game))
		red, green, blue := maxgame(sr)
		sum += (red * green * blue)
	}

	return fmt.Sprintf("%d", sum)
}