adventofcode/2024/03/main.go

package main

import (
	"fmt"
	"regexp"

	"aoc/helper"
)

func main() {
	corruptedMemory := helper.ReadLinesToString()

	// part 1
	instructions_result := findAndExecuteInstructions(corruptedMemory)
	fmt.Printf("Result: %d\n", instructions_result)

	// part 2
	enabled_instructions_result := findAndExecuteEnabledInstructions(corruptedMemory)
	fmt.Printf("Result (only enabled): %d\n", enabled_instructions_result)
}

func findAndExecuteInstructions(memory string) (res int) {
	// find all `mul()` and save numbers as MatchGroup 1 + 2
	re := regexp.MustCompile(`mul\((\d{1,3}),(\d{1,3})\)`)
	instructions := re.FindAllStringSubmatch(memory, -1)

	for _, inst := range instructions {
		res += helper.ToInt(inst[1]) * helper.ToInt(inst[2])
	}

	return res
}

func findAndExecuteEnabledInstructions(memory string) (res int) {
	// find all `mul()` and save numbers as MatchGroup 1 + 2
	// save `do()` and `dont()` in MatchGroup 0
	re := regexp.MustCompile(`mul\((\d{1,3}),(\d{1,3})\)|do\(\)|don't\(\)`)
	instructions := re.FindAllStringSubmatch(memory, -1)

	enabled := true
	for _, inst := range instructions {
		switch inst[0] {
		case "do()":
			enabled = true
		case "don't()":
			enabled = false
		default:
			if enabled {
				res += helper.ToInt(inst[1]) * helper.ToInt(inst[2])
			}
		}
	}

	return res
}