aoc2024/day-20/internal/one/graph.go

package one

import (
	"slices"
	"strings"

	"github.com/onyx-and-iris/aoc2024/day-20/internal/point"

	"github.com/elliotchance/orderedmap/v3"
)

type graph struct {
	start, end point.Point
	data       []string
}

func newGraph(data []string) *graph {
	return &graph{data: data}
}

func (g *graph) String() string {
	return strings.Join(g.data, "\n")
}

func (g *graph) isOutOfBounds(p point.Point) bool {
	return p.X < 1 || p.Y < 1 || p.Y >= len(g.data)-1 || p.X >= len(g.data[p.Y])-1
}

func (g *graph) valueAt(p point.Point) rune {
	return rune(g.data[p.Y][p.X])
}

func (g *graph) isValidCheatPosition(p point.Point) bool {
	allowed := []rune{'.', 'S', 'E'}

	ns := neighbours(p)

	return slices.Contains(allowed, g.valueAt(ns[N])) && slices.Contains(allowed, g.valueAt(ns[S])) ||
		slices.Contains(allowed, g.valueAt(ns[W])) && slices.Contains(allowed, g.valueAt(ns[E]))
}

func (g *graph) getConnectingPoint(dir direction, p point.Point) point.Point {
	ns := neighbours(p)

	return ns[dir]
}

func (g *graph) set(p point.Point, value rune) {
	g.data[p.Y] = replaceAtIndex(g.data[p.Y], value, p.X)
}

func (g *graph) path(
	current point.Point,
	om *orderedmap.OrderedMap[point.Point, int],
	dist int,
) *orderedmap.OrderedMap[point.Point, int] {
	if current == g.end {
		return om
	}

	var n point.Point
	for _, n = range neighbours(current) {
		_, ok := om.Get(n)
		if ok {
			continue
		}

		if g.valueAt(n) == '.' || g.valueAt(n) == 'E' {
			break
		}
	}
	om.Set(n, dist)

	return g.path(n, om, dist+1)
}

func (g *graph) debug(path *orderedmap.OrderedMap[point.Point, int]) string {
	temp := slices.Clone(g.data)
	for n := range path.Keys() {
		if g.valueAt(n) == cheatChar {
			continue
		}
		temp[n.Y] = replaceAtIndex(temp[n.Y], 'O', n.X)
	}
	return strings.Join(temp, "\n")
}