Advent Of Code 2023 - Day 2

aoc2023_d2.go

package d2

import (
	"bufio"
	"bytes"
	"io"
	"regexp"
	"strconv"
)

func Must(err error) {
	if err != nil {
		panic(err)
	}
}

const (
	Red   = 12
	Green = 13
	Blue  = 14
)

var allowed map[string]int = map[string]int{
	"red":   Red,
	"green": Green,
	"blue":  Blue,
}

func d2_1(r io.Reader) interface{} {
	reNums := regexp.MustCompile(`(Game \d+: )`)

	fileScanner := bufio.NewScanner(r)
	fileScanner.Split(bufio.ScanLines)

	possibleGamesSum := 0
	counter := 0
	for fileScanner.Scan() {
		gamePossible := true
		counter++

		databytes := fileScanner.Bytes()
		databytes = reNums.ReplaceAll(databytes, []byte(``))
		groups := bytes.Split(databytes, []byte(`; `))
		for i := range groups {
			if !gamePossible {
				break
			}
			picks := bytes.Split(groups[i], []byte(`, `))
			for j := range picks {
				if !gamePossible {
					break
				}
				numCol := bytes.Split(picks[j], []byte(` `))
				num, err := strconv.Atoi(string(numCol[0]))
				Must(err)
				limit := allowed[string(numCol[1])]
				gamePossible = num <= limit
			}
		}
		if gamePossible {
			possibleGamesSum += counter
		}
	}
	return possibleGamesSum
}

func getPower(minNums map[string]int) int {
	return minNums["red"] * minNums["green"] * minNums["blue"]
}
func getSum(numbers []int) int {
	total := 0
	for _, num := range numbers {
		total += num
	}
	return total
}

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

func d2_2(r io.Reader) interface{} {
	reNums := regexp.MustCompile(`(Game \d+: )`)

	fileScanner := bufio.NewScanner(r)
	fileScanner.Split(bufio.ScanLines)

	counter := 0
	powers := []int{}
	for fileScanner.Scan() {
		minNumsPreGame := map[string]int{
			"red":   0,
			"green": 0,
			"blue":  0,
		}
		counter++

		databytes := fileScanner.Bytes()
		databytes = reNums.ReplaceAll(databytes, []byte(``))
		groups := bytes.Split(databytes, []byte(`; `))
		for i := range groups {
			picks := bytes.Split(groups[i], []byte(`, `))
			for j := range picks {
				numCol := bytes.Split(picks[j], []byte(` `))
				num, err := strconv.Atoi(string(numCol[0]))
				Must(err)
				minNumsPreGame[string(numCol[1])] = max(minNumsPreGame[string(numCol[1])], num)
			}
		}

		powers = append(powers, getPower(minNumsPreGame))
	}
	return getSum(powers)
}