aoc2023/day-8/util.go

package main

import (
	"bufio"
	"log"
	"os"
	"regexp"
)

// readlines reads lines from stdin.
// returns input as an array of strings
func readlines() []string {
	lines := []string{}

	scanner := bufio.NewScanner(os.Stdin)
	for scanner.Scan() {
		lines = append(lines, scanner.Text())
	}

	if err := scanner.Err(); err != nil {
		log.Fatal(err)
	}

	return lines
}

var r = regexp.MustCompile(`(?P<identifier>[A-Z0-9]{3}) = \((?P<entry>[A-Z0-9]{3}), (?P<exit>[A-Z0-9]{3})\)`)

func parselines(lines []string) {
	directions = lines[0]

	steps = make(map[string][]string, len(lines[2:]))
	for _, line := range lines[2:] {
		m := r.FindStringSubmatch(line)
		if len(m) > 0 {
			steps[m[1]] = []string{m[2], m[3]}
		}
	}
}