Day 12: Part 1 and 2

Signed-off-by: James Griffin <james@unsupervised.ca>

main.go

@@ -3,7 +3,7 @@ package main
 import (
 	"fmt"
 
-	"github.com/thatguygriff/aoc2020/eleven"
+	"github.com/thatguygriff/aoc2020/twelve"
 )
 
 func main() {
@@ -48,6 +48,10 @@ func main() {
 	// fmt.Println(ten.PartTwo())
 
 	// Day 11
-	fmt.Println(eleven.PartOne())
+	// fmt.Println(eleven.PartOne())
-	fmt.Println(eleven.PartTwo())
+	// fmt.Println(eleven.PartTwo())
+
+	// Day 12
+	fmt.Println(twelve.PartOne())
+	fmt.Println(twelve.PartTwo())
 }

twelve/day_twelve.go

@@ -0,0 +1,188 @@
+package twelve
+
+import (
+	"bufio"
+	"fmt"
+	"math"
+	"os"
+	"strconv"
+)
+
+type instruction struct {
+	action string
+	value  int
+}
+
+type waypoint struct {
+	x, y int
+}
+
+type boat struct {
+	orientation int
+	orders      []instruction
+	x, y        int
+	waypoint    waypoint
+}
+
+func (b *boat) load(filename string) error {
+	file, err := os.Open(filename)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		amount, err := strconv.Atoi(scanner.Text()[1:])
+		if err != nil {
+			return err
+		}
+
+		b.orders = append(b.orders, instruction{
+			action: scanner.Text()[:1],
+			value:  amount,
+		})
+	}
+
+	return nil
+}
+
+func loadBoat(filename string) (*boat, error) {
+	b := &boat{
+		waypoint: waypoint{
+			x: 10,
+			y: 1,
+		},
+	}
+
+	err := b.load(filename)
+	if err != nil {
+		return nil, err
+	}
+
+	return b, nil
+}
+
+func (b *boat) advance(distance int) {
+	if b.orientation > 315 || b.orientation < 45 {
+		b.x += distance
+		return
+	}
+
+	if b.orientation > 45 && b.orientation < 135 {
+		b.y += distance
+		return
+	}
+
+	if b.orientation > 135 && b.orientation < 225 {
+		b.x -= distance
+	}
+
+	if b.orientation > 225 && b.orientation < 315 {
+		b.y -= distance
+	}
+}
+
+func (b *boat) navigate() int {
+	for _, o := range b.orders {
+		switch o.action {
+		case "F":
+			b.advance(o.value)
+		case "N":
+			b.y += o.value
+		case "S":
+			b.y -= o.value
+		case "E":
+			b.x += o.value
+		case "W":
+			b.x -= o.value
+		case "L":
+			b.orientation += o.value
+		case "R":
+			b.orientation -= o.value
+		}
+
+		for b.orientation >= 360 {
+			b.orientation -= 360
+		}
+
+		for b.orientation < 0 {
+			b.orientation += 360
+		}
+	}
+
+	return int(math.Abs(float64(b.x))) + int(math.Abs(float64(b.y)))
+}
+
+func (b *boat) rotate(degrees int) {
+	newX, newY := b.waypoint.x, b.waypoint.y
+
+	if degrees == 90 || degrees == -270 {
+		newX = b.waypoint.y * -1
+		newY = b.waypoint.x
+	}
+
+	if degrees == 180 || degrees == -180 {
+		newX = b.waypoint.x * -1
+		newY = b.waypoint.y * -1
+	}
+
+	if degrees == 270 || degrees == -90 {
+		newX = b.waypoint.y
+		newY = b.waypoint.x * -1
+	}
+
+	b.waypoint.x = newX
+	b.waypoint.y = newY
+}
+
+func (b *boat) waypointNavigate() int {
+	for _, o := range b.orders {
+		switch o.action {
+		case "F":
+			b.x += o.value * b.waypoint.x
+			b.y += o.value * b.waypoint.y
+		case "N":
+			b.waypoint.y += o.value
+		case "S":
+			b.waypoint.y -= o.value
+		case "E":
+			b.waypoint.x += o.value
+		case "W":
+			b.waypoint.x -= o.value
+		case "L":
+			b.rotate(o.value)
+		case "R":
+			b.rotate(o.value * -1)
+		}
+
+		for b.orientation >= 360 {
+			b.orientation -= 360
+		}
+
+		for b.orientation < 0 {
+			b.orientation += 360
+		}
+	}
+	return int(math.Abs(float64(b.x))) + int(math.Abs(float64(b.y)))
+}
+
+// PartOne What is the Manhatten distance that the boat travelled?
+func PartOne() string {
+	b, err := loadBoat("twelve/input.txt")
+	if err != nil {
+		return err.Error()
+	}
+
+	return fmt.Sprintf("The boat travelled a manhattan distance of %d", b.navigate())
+}
+
+// PartTwo What is the Manhatten distance that the boat travelled using a waypoint?
+func PartTwo() string {
+	b, err := loadBoat("twelve/input.txt")
+	if err != nil {
+		return err.Error()
+	}
+
+	return fmt.Sprintf("The boat travelled a manhattan distance of %d using a waypoint", b.waypointNavigate())
+}

twelve/day_twelve_test.go

@@ -0,0 +1,36 @@
+package twelve
+
+import "testing"
+
+func Test_load_boat(t *testing.T) {
+	b, err := loadBoat("sample.txt")
+	if err != nil {
+		t.Logf(err.Error())
+		t.FailNow()
+	}
+
+	if len(b.orders) != 5 {
+		t.Logf("Expected 5 orders, got %d", len(b.orders))
+		t.FailNow()
+	}
+}
+
+func Test_boat_navigate(t *testing.T) {
+	b, _ := loadBoat("sample.txt")
+
+	result := b.navigate()
+	if result != 25 {
+		t.Logf("Expected a navigation result of 25, got %d", result)
+		t.FailNow()
+	}
+}
+
+func Test_waypoint_navigate(t *testing.T) {
+	b, _ := loadBoat("sample.txt")
+
+	result := b.waypointNavigate()
+	if result != 286 {
+		t.Logf("Expected a navigation result of 286, got %d", result)
+		t.FailNow()
+	}
+}

twelve/input.txt

@@ -0,0 +1,791 @@
+F40
+N1
+W1
+F95
+W2
+N5
+R90
+N3
+E3
+F21
+E3
+F44
+W3
+R90
+N2
+L180
+E5
+F99
+W1
+F11
+R90
+N4
+F45
+S5
+L180
+W1
+R180
+E5
+R90
+F5
+S4
+E3
+S4
+L180
+W5
+F26
+F1
+S3
+L180
+F79
+R90
+S5
+R90
+E5
+L180
+W4
+F12
+N5
+E4
+F31
+S5
+W2
+F93
+W2
+F8
+S2
+E5
+F100
+L90
+F10
+R90
+N1
+F15
+S3
+E4
+L90
+L180
+S3
+E5
+R90
+F13
+N4
+F15
+L90
+W4
+N4
+W1
+S5
+F44
+W4
+F68
+N2
+W4
+F58
+L90
+E5
+F81
+S5
+L90
+S1
+F95
+R90
+E3
+R180
+F81
+R90
+S3
+E3
+L180
+W4
+W3
+N1
+W5
+R270
+W3
+N4
+W3
+N4
+F47
+E3
+R90
+F86
+S4
+N1
+R180
+E2
+N1
+S5
+R90
+N4
+L90
+E3
+R180
+N1
+W1
+N3
+E5
+N2
+F9
+N4
+R90
+F36
+E2
+S1
+R90
+N2
+F76
+F88
+E5
+F78
+W4
+F53
+N1
+W1
+R90
+R180
+N4
+W5
+S1
+N2
+E3
+F83
+L90
+E3
+L90
+W2
+L90
+N1
+W2
+F21
+R90
+F58
+S3
+F100
+S5
+F78
+S5
+R90
+E5
+R90
+W5
+W1
+L90
+F23
+L90
+F56
+W3
+F8
+W2
+N5
+F39
+S5
+F84
+N4
+R90
+N4
+F18
+S4
+F50
+S1
+E3
+S5
+L90
+N2
+W2
+N1
+F86
+R90
+S1
+R90
+L90
+W2
+F100
+E4
+L180
+F100
+E1
+S5
+W2
+L90
+N4
+E4
+R90
+F94
+W5
+S5
+L180
+W5
+S5
+L90
+S3
+R180
+E2
+F22
+R90
+E4
+F65
+N1
+E5
+F82
+W3
+F100
+E1
+F87
+L90
+S4
+W1
+F10
+W3
+S2
+F9
+E2
+F49
+F35
+E1
+R90
+F6
+W4
+F60
+R90
+S1
+F45
+W4
+F44
+E3
+L90
+W2
+N3
+L90
+N2
+W1
+N2
+W2
+S4
+E4
+W5
+R90
+E4
+L90
+F16
+W5
+S3
+N5
+L90
+F83
+W4
+L90
+E2
+F25
+W3
+R270
+W3
+L90
+N5
+F36
+S4
+R90
+F15
+R90
+S2
+L90
+E5
+F25
+S3
+F2
+N4
+W1
+N2
+F6
+S3
+R90
+L90
+W2
+N2
+E5
+S3
+L90
+F31
+W4
+L90
+N4
+F30
+S3
+R90
+S3
+L180
+W4
+N4
+F72
+W3
+S1
+R90
+F60
+E4
+R180
+W4
+S1
+W4
+R90
+F10
+E3
+F58
+E5
+N2
+W5
+L180
+N1
+E1
+R90
+W5
+N1
+E3
+L90
+N2
+R90
+E2
+R180
+S1
+R90
+F91
+L90
+W4
+N3
+L270
+F52
+W2
+R90
+F92
+N4
+E5
+F46
+N2
+F36
+W3
+L90
+N5
+F60
+N1
+S3
+F94
+L180
+S1
+R270
+R180
+F26
+S1
+F23
+E5
+R90
+F27
+S3
+L90
+F8
+E5
+F5
+S1
+R90
+F99
+W3
+F47
+W3
+S3
+W1
+L180
+W3
+R180
+F41
+L180
+E2
+L180
+N5
+R90
+F17
+S2
+E2
+F2
+R90
+N2
+F53
+S4
+L90
+F87
+R180
+E1
+S4
+F43
+R90
+F45
+W4
+F7
+W5
+L90
+W4
+L90
+E3
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+E3
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+F14
+N1
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+E4
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+N1
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+F98
+L180
+E5
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+E4
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+E1
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+E3
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+F21
+F84
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+S5
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+F68
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+N2
+F25
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+F89
+W4
+F76
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+F73
+E1
+N3
+L90
+E4
+F97
+L180
+N2
+R180
+E1
+F88
+E3
+N5
+W2
+F62
+S3
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+N1
+N3
+N4
+F3
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+F28
+L90
+S4
+E1
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+E4
+F63
+R90
+N2
+R90
+F22
+N3
+L90
+W4
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+F67
+W5
+N4
+F44
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+F64
+L180
+W3
+N2
+W1
+F63
+N3
+R90
+S5
+R90
+F20
+L180
+L270
+S1
+L90
+F66
+W5
+R90
+N1
+L180
+W4
+F94
+S3
+R180
+F18
+L90
+F29
+S3
+L90
+S4
+F74
+L90
+F85
+F35
+R90
+S4
+F68
+R90
+F44
+S2
+W4
+S2
+F27
+R90
+E5
+F30
+E1
+L90
+W4
+F39
+N3
+L90
+E1
+S4
+F87
+W2
+L90
+N3
+W1
+F51
+W1
+L180
+F24
+N2
+E1
+N2
+F4
+R90
+E3
+S1
+F69
+R90
+E4
+F31
+L90
+S3
+E3
+E5
+L90
+F75
+E4
+L90
+F14
+L90
+N1
+R90
+F36
+S4
+F49
+L90
+N5
+W3
+R90
+F35
+L180
+R180
+F26
+W3
+F16
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+F90
+E3
+N3
+F87
+N5
+L180
+F4
+R90
+N1
+E4
+N5
+F93
+W1
+N4
+L90
+F35
+L90
+W1
+E3
+N5
+W5
+F5
+S1
+W1
+N1
+F61
+S1
+W2
+N1
+R90
+F26
+R90
+L90
+W4
+F12
+R90
+W1
+R90
+F18
+E1
+F14
+N3
+W3
+S2
+F25
+E5
+F89
+W5
+L90
+S4
+F38
+L180
+F98
+W3
+S1
+F77
+R270
+E2
+F95
+W1
+F56
+N4
+R180
+E3
+L270
+E1
+F6
+S3
+L180
+E5
+R180
+E1
+N2
+L180
+E4
+S3
+E2
+L180
+F72
+N4
+R90
+L90
+W4
+F82
+S3
+R270
+F32
+F39
+L90
+N5
+W1
+L90
+N3
+F95
+L180
+S5
+L90
+F46
+E1
+L90
+W2
+S5
+L90
+S5
+F77
+L90
+N4
+E3
+N1
+F39
+R90
+R90
+F40
+L90
+N4
+W1
+F7
+E4
+S5
+E5
+N1
+F96
+E4
+F10
+F8
+S5
+E5
+F26
+S4
+R90
+S2
+F61
+W4
+S4
+R90
+E2
+F39
+S5
+R90
+S4
+F83
+S5
+F18
+S3
+E5
+R180
+F7

twelve/sample.txt

@@ -0,0 +1,5 @@
+F10
+N3
+F7
+R90
+F11