Add solution for Day 19

Signed-off-by: Knut Ahlers <knut@ahlers.me>

day19.go

@@ -0,0 +1,231 @@
+package aoc2019
+
+import (
+	"io/ioutil"
+	"log"
+	"math"
+	"strings"
+
+	"github.com/pkg/errors"
+)
+
+type day19Fact uint8
+
+const (
+	day19FactNoMoveDownPossible day19Fact = 1 << iota
+	day19FactNoMoveLeftPossible
+	day19FactNoMoveRightPossible
+	day19FactNoMoveTopPossible
+	day19FactOriginNotInBeam
+	day19FactX100NotInBeam
+	day19FactY100NotInBeam
+)
+
+func (f day19Fact) has(t day19Fact) bool { return f&t != 0 }
+func (f day19Fact) String() string {
+	return map[day19Fact]string{
+		day19FactNoMoveDownPossible:  "NoMoveDownPossible",
+		day19FactNoMoveLeftPossible:  "NoMoveLeftPossible",
+		day19FactNoMoveRightPossible: "NoMoveRightPossible",
+		day19FactNoMoveTopPossible:   "NoMoveTopPossible",
+		day19FactOriginNotInBeam:     "OriginNotInBeam",
+		day19FactX100NotInBeam:       "X100NotInBeam",
+		day19FactY100NotInBeam:       "Y100NotInBeam",
+	}[f]
+}
+
+func day19CountFieldsInTractorBeam(code []int64, maxX, maxY int64) int64 {
+	var count int64
+
+	for y := int64(0); y <= maxY; y++ {
+		for x := int64(0); x <= maxX; x++ {
+
+			var (
+				in  = make(chan int64)
+				out = make(chan int64)
+			)
+			go executeIntcode(code, in, out)
+
+			// Submit coordinates
+			in <- x
+			in <- y
+
+			// Count fields with tractor beam
+			o := <-out
+			count += o
+		}
+	}
+
+	return count
+}
+
+func day19Find100x100ShipPlace(code []int64) int64 {
+	var (
+		x, y     int64
+		bvL, bvR int64
+	)
+
+	getBeamVectors := func() {
+		for x := int64(0); x <= math.MaxInt64; x++ {
+
+			var (
+				in  = make(chan int64)
+				out = make(chan int64)
+			)
+			go executeIntcode(code, in, out)
+
+			// Submit coordinates
+			in <- x
+			in <- 100
+
+			// Count fields with tractor beam
+			o := <-out
+			switch {
+			case o == 0 && bvR == 0:
+				// Did not yet find the beam
+			case o == 1 && bvL == 0:
+				// Left beam end has not been set
+				bvL, bvR = x, x
+			case o == 1 && x > bvR:
+				// New right "edge" found
+				bvR = x
+			case 0 == 0 && bvR > 0:
+				// End of right edge found, end
+				return
+			}
+
+		}
+	}
+
+	checkCoordinate := func(x, y int64) day19Fact {
+		var facts day19Fact
+
+		for flag, c := range map[day19Fact][2]int64{
+			day19FactNoMoveDownPossible:  {x, y + 100},
+			day19FactNoMoveLeftPossible:  {x - 1, y + 99},
+			day19FactNoMoveRightPossible: {x + 100, y},
+			day19FactNoMoveTopPossible:   {x + 99, y - 1},
+			day19FactOriginNotInBeam:     {x, y},
+			day19FactX100NotInBeam:       {x + 99, y},
+			day19FactY100NotInBeam:       {x, y + 99},
+		} {
+			if c[0] < 0 || c[1] < 0 {
+				// Never check negative coordinates
+				facts |= flag
+				continue
+			}
+
+			var (
+				in  = make(chan int64)
+				out = make(chan int64)
+			)
+			defer close(in)
+
+			go executeIntcode(code, in, out)
+
+			// Submit coordinates
+			in <- c[0]
+			in <- c[1]
+
+			o := <-out
+			if o == 0 {
+				facts |= flag
+			}
+
+		}
+
+		return facts
+	}
+
+	// Initially get vectors for beam edges
+	getBeamVectors()
+
+	// Try to get to the best position through movement
+	var success bool
+	for !success {
+		var f = checkCoordinate(x, y)
+
+		switch {
+		case f.has(day19FactOriginNotInBeam):
+			panic("Origin placed outside beam")
+
+		case f.has(day19FactX100NotInBeam) || f.has(day19FactY100NotInBeam):
+			// Ship does not fit, move further away
+			y += 100
+			x = ((bvL * (y / 100)) + (bvR * (y / 100))) / 2
+
+		case !f.has(day19FactNoMoveTopPossible):
+			// Ship can be moved up in beam
+			y -= 1
+
+		case !f.has(day19FactNoMoveLeftPossible):
+			// Ship can be moved left in beam
+			x -= 1
+
+		case f.has(day19FactNoMoveTopPossible) && f.has(day19FactNoMoveLeftPossible):
+			// No movement towards ship is possible and ship fits in: Perfect
+			success = true
+
+		}
+	}
+
+	log.Printf("Result before force-move: x=%d y=%d res=%d", x, y, x*10000+y)
+
+	// This MIGHT not be the perfect position, force further movement
+	// by ignoring some factors set above in order to compensate inaccurate
+	// vectors due to working with integers only
+	var fX, fY = x, y
+	for success {
+		var f = checkCoordinate(fX, fY)
+
+		if !f.has(day19FactX100NotInBeam) && !f.has(day19FactY100NotInBeam) {
+			// Found a better position through forcing
+			x, y = fX, fY
+		}
+
+		switch {
+		case !f.has(day19FactNoMoveTopPossible):
+			// Ship can be moved up in beam
+			fY -= 1
+
+		case f.has(day19FactOriginNotInBeam):
+			// No further tests, there will be no better position
+			success = false
+
+		default:
+			fX -= 1
+		}
+	}
+
+	log.Printf("Result after force-move:  x=%d y=%d res=%d", x, y, x*10000+y)
+
+	return x*10000 + y
+}
+
+func solveDay19Part1(inFile string) (int64, error) {
+	rawCode, err := ioutil.ReadFile(inFile)
+	if err != nil {
+		return 0, errors.Wrap(err, "Unable to read intcode")
+	}
+
+	code, err := parseIntcode(strings.TrimSpace(string(rawCode)))
+	if err != nil {
+		return 0, errors.Wrap(err, "Unable to parse intcode")
+	}
+
+	return day19CountFieldsInTractorBeam(code, 49, 49), nil
+}
+
+func solveDay19Part2(inFile string) (int64, error) {
+	rawCode, err := ioutil.ReadFile(inFile)
+	if err != nil {
+		return 0, errors.Wrap(err, "Unable to read intcode")
+	}
+
+	code, err := parseIntcode(strings.TrimSpace(string(rawCode)))
+	if err != nil {
+		return 0, errors.Wrap(err, "Unable to parse intcode")
+	}
+
+	return day19Find100x100ShipPlace(code), nil
+}

day19_input.txt

@@ -0,0 +1 @@
+109,424,203,1,21101,11,0,0,1105,1,282,21102,1,18,0,1105,1,259,2102,1,1,221,203,1,21102,1,31,0,1105,1,282,21102,38,1,0,1105,1,259,20101,0,23,2,22102,1,1,3,21101,1,0,1,21101,57,0,0,1105,1,303,2101,0,1,222,21002,221,1,3,21002,221,1,2,21102,1,259,1,21101,0,80,0,1105,1,225,21102,83,1,2,21102,1,91,0,1106,0,303,2101,0,1,223,20102,1,222,4,21101,0,259,3,21101,0,225,2,21101,225,0,1,21101,118,0,0,1106,0,225,20101,0,222,3,21101,34,0,2,21101,133,0,0,1105,1,303,21202,1,-1,1,22001,223,1,1,21102,1,148,0,1106,0,259,1201,1,0,223,20102,1,221,4,20101,0,222,3,21101,12,0,2,1001,132,-2,224,1002,224,2,224,1001,224,3,224,1002,132,-1,132,1,224,132,224,21001,224,1,1,21101,195,0,0,105,1,108,20207,1,223,2,20101,0,23,1,21102,1,-1,3,21102,214,1,0,1105,1,303,22101,1,1,1,204,1,99,0,0,0,0,109,5,1202,-4,1,249,22101,0,-3,1,22101,0,-2,2,21201,-1,0,3,21101,0,250,0,1105,1,225,21201,1,0,-4,109,-5,2106,0,0,109,3,22107,0,-2,-1,21202,-1,2,-1,21201,-1,-1,-1,22202,-1,-2,-2,109,-3,2106,0,0,109,3,21207,-2,0,-1,1206,-1,294,104,0,99,22101,0,-2,-2,109,-3,2106,0,0,109,5,22207,-3,-4,-1,1206,-1,346,22201,-4,-3,-4,21202,-3,-1,-1,22201,-4,-1,2,21202,2,-1,-1,22201,-4,-1,1,21201,-2,0,3,21101,343,0,0,1105,1,303,1105,1,415,22207,-2,-3,-1,1206,-1,387,22201,-3,-2,-3,21202,-2,-1,-1,22201,-3,-1,3,21202,3,-1,-1,22201,-3,-1,2,21201,-4,0,1,21101,384,0,0,1105,1,303,1106,0,415,21202,-4,-1,-4,22201,-4,-3,-4,22202,-3,-2,-2,22202,-2,-4,-4,22202,-3,-2,-3,21202,-4,-1,-2,22201,-3,-2,1,21202,1,1,-4,109,-5,2106,0,0

day19_test.go

@@ -0,0 +1,21 @@
+package aoc2019
+
+import "testing"
+
+func TestCalculateDay19_Part1(t *testing.T) {
+	res, err := solveDay19Part1("day19_input.txt")
+	if err != nil {
+		t.Fatalf("Day 19 solver failed: %s", err)
+	}
+
+	t.Logf("Solution Day 19 Part 1: %d", res)
+}
+
+func TestCalculateDay19_Part2(t *testing.T) {
+	res, err := solveDay19Part2("day19_input.txt")
+	if err != nil {
+		t.Fatalf("Day 19 solver failed: %s", err)
+	}
+
+	t.Logf("Solution Day 19 Part 2: %d", res)
+}