chore: add day 18 pt 2

day18/main.go

@@ -5,9 +5,12 @@ import (
 	_ "embed"
 	"encoding/hex"
 	"fmt"
+	"os"
+	"strconv"
 	"strings"
 
 	aoc "go.sour.is/advent-of-code"
+	"golang.org/x/exp/maps"
 )
 
 // var log = aoc.Log
@@ -24,6 +27,7 @@ func (r result) String() string { return fmt.Sprintf("%#v", r) }
 func run(scan *bufio.Scanner) (*result, error) {
 
 	var vecs []vec
+	var vecs2 []vec
 
 	for scan.Scan() {
 		text := scan.Text()
@@ -35,7 +39,7 @@ func run(scan *bufio.Scanner) (*result, error) {
 		var s string
 		v := vec{}
 		s, text, _ = strings.Cut(text, " ")
-		v.Direction = direction(s)
+		v.Direction = direction(s[0])
 		s, text, _ = strings.Cut(text, " ")
 		v.Steps = aoc.Atoi(s)
 		_, text, _ = strings.Cut(text, "#")
@@ -43,32 +47,47 @@ func run(scan *bufio.Scanner) (*result, error) {
 		b, _ := hex.DecodeString(s)
 		copy(v.Color[:], b)
 		vecs = append(vecs, v)
+		vecs2 = append(vecs2, fromColor(s))
 	}
+	return &result{
+		valuePT1: findArea(vecs),
+		valuePT2: skip("AOC_DAY18P2", func() int { return findArea(vecs2) }),
+	}, nil
+}
 
+func findArea(vecs []vec) int {
 	var points []point
 
 	var x, y int
 	var minX, minY int
-	for i, v := range vecs {
-		fmt.Println("pt ", i, v)
-
+	last := direction('S')
+	for _, v := range vecs {
+		// fmt.Println("pt ", i, v)
 		for i := 0; i < v.Steps; i++ {
 			switch v.Direction {
-			case "U":
+			case 'U':
 				y++
-			case "D":
+			case 'D':
 				y--
-			case "R":
+			case 'R':
 				x++
-			case "L":
+			case 'L':
 				x--
 			}
+			// fmt.Println("pt ", i, y, x)
 
 			minX = min(minX, x)
 			minY = min(minY, y)
-			points = append(points, point{d: v.Direction, x: x, y: y, color: v.Color})
+			if len(points) > 0 {
+				points[len(points)-1].d = v.Direction
+			}
+			points = append(points, point{d: v.Direction, w: opposite(v.Direction), x: x, y: y, color: v.Color})
+			last = v.Direction
 		}
 	}
+	_ = last
+	// points[0].w = last
+	points[len(points)-1].d = points[0].w
 
 	adjX := aoc.ABS(min(0, minX))
 	adjY := aoc.ABS(min(0, minY))
@@ -81,9 +100,10 @@ func run(scan *bufio.Scanner) (*result, error) {
 	maxX, maxY := 0, 0
 
 	for i, p := range points {
-		// fmt.Println("raw", i, p)
+
 		p.x += adjX
 		p.y += adjY
+		// fmt.Println("raw", i, p.x, p.y, string(p.w), string(p.d))
 
 		maxX = max(maxX, p.x)
 		maxY = max(maxY, p.y)
@@ -98,69 +118,78 @@ func run(scan *bufio.Scanner) (*result, error) {
 			trace[p.y] = row
 		}
 	}
+	fmt.Println("maxX", maxX, "maxY", maxY)
 
 	area := 0
 
-	for y := 0; y <= maxY; y++ {
+	for y := maxY; y >= 0; y-- {
 		row, ok := trace[y]
 		if !ok {
 			continue
 		}
 
 		var last direction
-		p, inLoop := row[0]
+		p := row[0]
 		last = p.d
+		inLoop := false
 
 		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":
+				// fmt.Println("vec", string(p.w), string(p.d))
+				switch string([]rune{rune(p.w), rune(p.d)}) {
+				case "LD", "DL", "UD", "DU", "RD", "UU", "DR":
 					inLoop = !inLoop
 				}
 				if last != p.d {
 					last = p.d
 				}
-				fmt.Print(p.d)
-				if inLoop {
-					area++
-				}
-				continue
+
+				// fmt.Print(string(p.w)+string(p.d))
+
+				// On loop
+				area++
+
+				continue // 203338
 			}
-			last = direction(" ")
+			last = direction('0')
 
 			if inLoop {
 				area++
-				fmt.Print(".")
-			} else {
-				fmt.Print(" ")
+				// fmt.Print("XX")
+				// } else {
+				// 	fmt.Print("..")
 			}
 
 		}
-		fmt.Println("")
+		// fmt.Println("")
+		fmt.Println(y, area)
 	}
-
-	// 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
+	return area
 }
 
-type direction string
+type direction rune
 
 const (
-	U direction = "U"
-	D direction = "D"
-	L direction = "L"
-	R direction = "R"
+	U direction = 'U'
+	D direction = 'D'
+	L direction = 'L'
+	R direction = 'R'
 )
 
+func opposite(d direction) direction {
+	switch d {
+	case U:
+		return D
+	case D:
+		return U
+	case L:
+		return R
+	case R:
+		return L
+	}
+	return '0'
+}
+
 type vec struct {
 	Direction direction
 	Steps     int
@@ -174,42 +203,32 @@ type point struct {
 	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})
+func fromColor(c string) vec {
+	steps, _ := strconv.ParseInt(c[:5], 16, 64)
 
-	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})
+	d := '_'
+	switch c[5] {
+	case '0':
+		d = 'R'
+	case '1':
+		d = 'D'
+	case '2':
+		d = 'L'
+	case '3':
+		d = 'U'
 	}
 
-	if len(result) == 1 {
-		return result
+	return vec{
+		Direction: direction(d),
+		Steps:     int(steps),
 	}
-
-	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
+}
+
+func skip[T any](env string, fn func() T) T {
+	var zero T
+	if e, err := strconv.ParseBool(os.Getenv(env)); err == nil && e {
+		return zero
+	}
+
+	return fn()
 }

day18/main_test.go

@@ -3,6 +3,7 @@ package main
 import (
 	"bufio"
 	"bytes"
+	"os"
 	"testing"
 
 	_ "embed"
@@ -25,18 +26,20 @@ func TestExample(t *testing.T) {
 
 	t.Log(result)
 	is.Equal(result.valuePT1, 62)
-	is.Equal(result.valuePT2, 0)
+	is.Equal(result.valuePT2, 952408144115)
 }
 
 func TestSolution(t *testing.T) {
 	is := is.New(t)
 	scan := bufio.NewScanner(bytes.NewReader(input))
 
+	os.Setenv("AOC_DAY18P2", "1")
+
 	result, err := run(scan)
 	is.NoErr(err)
 
 	t.Log(result)
 	is.True(result.valuePT1 < 68834) // first attempt too high.
-	is.Equal(result.valuePT1, 0)
+	is.Equal(result.valuePT1, 46334)
 	is.Equal(result.valuePT2, 0)
 }