aoc2024/day-16/internal/two/util.go

package two

import (
	"bufio"
	"io"
	"strings"
)

func parseLines(r io.Reader) (*graph, error) {
	graph := newGraph()

	var linecount int
	scanner := bufio.NewScanner(r)
	for scanner.Scan() {
		line := scanner.Text()

		r, indx := indxForAny(line, []rune{'S', 'E'})
		if indx != -1 {
			if r == 'S' {
				graph.start = newNode(indx, linecount, E)
			} else {
				graph.end = newNode(indx, linecount, 0)
			}
		}

		graph.data = append(graph.data, line)

		linecount++
	}

	if err := scanner.Err(); err != nil {
		return nil, err
	}

	return graph, nil
}

func indxForAny(s string, runes []rune) (rune, int) {
	for _, r := range runes {
		indx := strings.Index(s, string(r))
		if indx != -1 {
			return r, indx
		}
	}
	return 0, -1
}

func replaceAtIndex(s string, r rune, i int) string {
	out := []rune(s)
	out[i] = r
	return string(out)
}