advent-of-code/day18/main.go

package main

import (
	"bufio"
	_ "embed"
	"encoding/hex"
	"fmt"
	"strings"

	aoc "go.sour.is/advent-of-code"
)

// var log = aoc.Log

func main() { aoc.MustResult(aoc.Runner(run)) }

type result struct {
	valuePT1 int
	valuePT2 int
}

func (r result) String() string { return fmt.Sprintf("%#v", r) }

func run(scan *bufio.Scanner) (*result, error) {

	var vecs []vec

	for scan.Scan() {
		text := scan.Text()

		if len(text) == 0 {
			continue
		}

		var s string
		v := vec{}
		s, text, _ = strings.Cut(text, " ")
		v.Direction = direction(s)
		s, text, _ = strings.Cut(text, " ")
		v.Steps = aoc.Atoi(s)
		_, text, _ = strings.Cut(text, "#")
		s, _, _ = strings.Cut(text, ")")
		b, _ := hex.DecodeString(s)
		copy(v.Color[:], b)
		vecs = append(vecs, v)
	}

	var points []point

	var x, y int
	var minX, minY int
	for i, v := range vecs {
		fmt.Println("pt ", i, v)

		for i := 0; i < v.Steps; i++ {
			switch v.Direction {
			case "U":
				y++
			case "D":
				y--
			case "R":
				x++
			case "L":
				x--
			}

			minX = min(minX, x)
			minY = min(minY, y)
			points = append(points, point{d: v.Direction, x: x, y: y, color: v.Color})
		}
	}

	adjX := aoc.ABS(min(0, minX))
	adjY := aoc.ABS(min(0, minY))
	fmt.Println("minX", minX, "minY", minY)
	fmt.Println("adjX", adjX, "adjY", adjY)

	trace := make(map[int]map[int]point)

	minX, minY = 0, 0
	maxX, maxY := 0, 0

	for i, p := range points {
		// fmt.Println("raw", i, p)
		p.x += adjX
		p.y += adjY

		maxX = max(maxX, p.x)
		maxY = max(maxY, p.y)

		points[i] = p

		if row, ok := trace[p.y]; true {
			if !ok {
				row = make(map[int]point)
			}
			row[p.x] = p
			trace[p.y] = row
		}
	}

	area := 0

	for y := 0; y <= maxY; y++ {
		row, ok := trace[y]
		if !ok {
			continue
		}

		var last direction
		p, inLoop := row[0]
		last = p.d

		for x := 0; x <= maxX; x++ {
			if p, ok := row[x]; ok {
				switch last+p.d {
				case " U"," L", "UR":
					inLoop = true
				case "LD", " D", "RD":
					inLoop = !inLoop
				}
				if last != p.d {
					last = p.d
				}
				fmt.Print(p.d)
				if inLoop {
					area++
				}
				continue
			}
			last = direction(" ")

			if inLoop {
				area++
				fmt.Print(".")
			} else {
				fmt.Print(" ")
			}

		}
		fmt.Println("")
	}

	// for y := 0; y < len(trace); y++ {
	// 	rng := trace[y]
	// 	sort.Ints(rng)
	// 	for _, r := range ranges(rng) {
	// 		area += r[1] - r[0] + 1
	// 	}
	// }

	return &result{valuePT1: area}, nil
}

type direction string

const (
	U direction = "U"
	D direction = "D"
	L direction = "L"
	R direction = "R"
)

type vec struct {
	Direction direction
	Steps     int
	Color     [3]byte
}

type point struct {
	w     direction
	d     direction
	x, y  int
	color [3]byte
}

func ranges(rng []int) [][]int {
	// inLoop := true
	var mn int = rng[0]
	var last int = rng[0]
	var result [][]int
	result = append(result, []int{mn, mn})

	for _, i := range rng[1:] {
		if i-last == 1 {
			result[len(result)-1][1] = i
			last = i
			continue
		}

		last = i
		mn = i
		result = append(result, []int{mn, last})
	}

	if len(result) == 1 {
		return result
	}

	if len(result) == 2 {
		return [][]int{{result[0][0], result[1][1]}}
	}

	if len(result)%2 == 0 {
		var result2 [][]int
		for i := 0; i < len(result); i += 2 {
			result2 = append(result2, []int{result[i][0], result[i+1][1]})
		}

		return result2
	}

	fmt.Println("odd ranges", result)
	return nil
}