aoc2024/day-18/internal/two/solve.go

package two

import (
	"bytes"
	"fmt"

	"github.com/onyx-and-iris/aoc2024/day-18/internal/config"
	"github.com/onyx-and-iris/aoc2024/day-18/internal/point"
	log "github.com/sirupsen/logrus"
)

func Solve(buf []byte, config config.Config) (string, error) {
	r := bytes.NewReader(buf)
	graph, corruptedCoords, err := parseLines(r, config)
	if err != nil {
		return "", err
	}

	log.Debugf("start: %v end: %v", graph.start, graph.end)
	log.Debug(corruptedCoords)

	indx := runUntilNoPath(graph, corruptedCoords, config)
	return fmt.Sprintf("%d,%d", corruptedCoords[indx][0], corruptedCoords[indx][1]), nil
}

func runUntilNoPath(graph *graph, corruptedCoords [][]int, config config.Config) int {
	for i, coords := range corruptedCoords[config.NumCorruptions+1:] {
		nextCorruption := point.Point{X: coords[0], Y: coords[1]}

		log.Debugf("adding corruption %v", nextCorruption)
		graph.addCorruption(nextCorruption)

		ok := graph.bfs()
		if !ok {
			return config.NumCorruptions + i + 1
		}
	}
	return 0
}