advent_of_code/2023/01/main.go

package main

import (
	"bufio"
	"fmt"
	"os"
	"strings"
	"unicode"

	"github.com/fatih/color"
	"github.com/thoas/go-funk"
)

var numberstrings = [9]string{"one", "two", "three", "four", "five", "six", "seven", "eight", "nine"}

func readFileLines(filename string) ([]string, error) {
	var lines []string

	file, err := os.Open(filename)
	if err != nil {
		return lines, err
	}
	fileScanner := bufio.NewScanner(file)
	fileScanner.Split(bufio.ScanLines)

	for fileScanner.Scan() {
		lines = append(lines, fileScanner.Text())
	}

	return lines, nil
}

func getNumbersFromLines(lines []string) []int {
	var result []int
	for _, line := range lines {
		firstnum := -1
		lastnum := -1
		for _, char := range line {
			if unicode.IsDigit(rune(char)) {
				if firstnum == -1 {
					firstnum = int(char) - int('0')
				} else {
					lastnum = int(char) - int('0')
				}
			}
		}
		if lastnum == -1 {
			lastnum = firstnum
		}
		result = append(result, firstnum*10+lastnum)
	}
	return result
}

func getNumbersFromLinesPart2(lines []string) []int {
	var result []int
	for _, line := range lines {
		firstnum := -1
		lastnum := -1
		firstnumIndex := len(line)
		lastnumIndex := 0
		for idx, char := range line {
			if unicode.IsDigit(rune(char)) {
				if firstnum == -1 {
					firstnum = int(char) - int('0')
					firstnumIndex = idx
				} else {
					lastnum = int(char) - int('0')
					lastnumIndex = idx
				}
			}
		}
		if lastnum == -1 {
			lastnum = firstnum
			lastnumIndex = firstnumIndex
		}
		for idx, num := range numberstrings {
			stridx := strings.Index(line, num)
			if stridx != -1 && stridx < firstnumIndex {
				firstnum = idx + 1
				firstnumIndex = stridx
			}
			stridx = strings.LastIndex(line, num)
			if stridx > lastnumIndex {
				lastnum = idx + 1
				lastnumIndex = stridx
			}
		}
		if lastnum == -1 {
			lastnum = firstnum
		}
		result = append(result, firstnum*10+lastnum)
	}
	return result
}

func main() {
	redPrint := color.New(color.FgRed)
	yellowPrint := color.New(color.FgYellow)
	if len(os.Args) < 2 {
		redPrint.Fprintln(os.Stderr, "You must provide the input file")
		os.Exit(1)
	}
	lines, err := readFileLines(os.Args[1])
	if err != nil {
		redPrint.Fprintln(os.Stderr, "Could not read input file")
		os.Exit(1)
	}
	numbers := getNumbersFromLines(lines)
	sum := funk.Reduce(numbers, '+', 0)

	fmt.Print("Part 1: ")
	yellowPrint.Print(sum)
	fmt.Println()

	numbers2 := getNumbersFromLinesPart2(lines)
	sum2 := funk.Reduce(numbers2, '+', 0)

	fmt.Print("Part 2: ")
	yellowPrint.Print(sum2)
	fmt.Println()
}