adds 2021\17

2021/17/input.txt

@@ -0,0 +1 @@
+target area: x=287..309, y=-76..-48

2021/17/main.go

@@ -0,0 +1,166 @@
+package main
+
+import (
+	"fmt"
+	"math"
+
+	"github.com/jdrst/adventofgo/util"
+)
+
+func main() {
+	fmt.Printf("First part: %v\n", partOne(util.ReadFile("input.txt")))
+	fmt.Printf("Second part: %v\n", partTwo(util.ReadFile("input.txt")))
+}
+
+type foo struct {
+	initVelocity, t int
+}
+
+type bar struct {
+	xVel, yVel, t int
+}
+
+func partOne(file util.File) int {
+	lines := file.AsLines()
+	var xmin, xmax, ymin, ymax int
+	fmt.Sscanf(string(lines[0]), "target area: x=%d..%d, y=%d..%d", &xmin, &xmax, &ymin, &ymax)
+	xsize := util.Delta(xmax, xmin)
+	ysize := util.Delta(ymax, ymin)
+
+	target := make([][]util.Point, xsize+1)
+	for i := 0; i <= xsize; i++ {
+		target[i] = make([]util.Point, ysize+1)
+		for j := 0; j <= ysize; j++ {
+			target[i][j] = util.Point{X: xmin + i, Y: ymin + j}
+		}
+	}
+
+	possibleYs := []foo{}
+next:
+	for traj := ymin; traj < util.Abs(ymin); traj++ {
+		curr := traj
+		if curr <= ymax && curr >= ymin {
+			possibleYs = append(possibleYs, foo{initVelocity: traj, t: 0})
+		}
+		for t := 1; ; t++ {
+			dy := yy(traj, t)
+			curr += dy
+			if curr < ymin {
+				continue next
+			}
+			if curr <= ymax && curr >= ymin {
+				possibleYs = append(possibleYs, foo{initVelocity: traj, t: t})
+			}
+		}
+	}
+
+	possibleXYs := []bar{}
+	for _, t := range possibleYs {
+		for traj := 0; traj <= xmax; traj++ {
+			curr := traj
+			for i := 0; i < t.t; i++ {
+				dx := xx(traj, i)
+				if dx == 0 {
+					break
+				}
+				curr += dx
+			}
+			if curr <= xmax && curr >= xmin {
+				possibleXYs = append(possibleXYs, bar{xVel: traj, yVel: t.initVelocity, t: t.t})
+			}
+		}
+	}
+
+	maxY := math.MinInt
+	for _, xy := range possibleXYs {
+		curr := getHighestPointOfTrajectory(xy.yVel)
+		if curr > maxY {
+			maxY = curr
+		}
+	}
+	return maxY
+}
+
+func partTwo(file util.File) int {
+	lines := file.AsLines()
+	var xmin, xmax, ymin, ymax int
+	fmt.Sscanf(string(lines[0]), "target area: x=%d..%d, y=%d..%d", &xmin, &xmax, &ymin, &ymax)
+	xsize := util.Delta(xmax, xmin)
+	ysize := util.Delta(ymax, ymin)
+
+	target := make([][]util.Point, xsize+1)
+	for i := 0; i <= xsize; i++ {
+		target[i] = make([]util.Point, ysize+1)
+		for j := 0; j <= ysize; j++ {
+			target[i][j] = util.Point{X: xmin + i, Y: ymin + j}
+		}
+	}
+
+	possibleYs := []foo{}
+next:
+	for traj := ymin; traj < util.Abs(ymin); traj++ {
+		curr := traj
+		if curr <= ymax && curr >= ymin {
+			possibleYs = append(possibleYs, foo{initVelocity: traj, t: 0})
+		}
+		for t := 1; ; t++ {
+			dy := yy(traj, t)
+			curr += dy
+			if curr < ymin {
+				continue next
+			}
+			if curr <= ymax && curr >= ymin {
+				possibleYs = append(possibleYs, foo{initVelocity: traj, t: t})
+			}
+		}
+
+	}
+
+	possibleXYs := []bar{}
+	for _, t := range possibleYs {
+		for traj := 0; traj <= xmax; traj++ {
+			curr := traj
+			for i := 1; i <= t.t; i++ {
+				dx := xx(traj, i)
+				if dx == 0 {
+					break
+				}
+				curr += dx
+			}
+			if curr <= xmax && curr >= xmin {
+				possibleXYs = append(possibleXYs, bar{xVel: traj, yVel: t.initVelocity, t: t.t})
+			}
+		}
+	}
+
+	unique := map[util.Point]bool{}
+	for _, xy := range possibleXYs {
+		if _, exists := unique[util.Point{X: xy.xVel, Y: xy.yVel}]; exists {
+			continue
+		}
+		unique[util.Point{X: xy.xVel, Y: xy.yVel}] = true
+	}
+	return len(unique)
+}
+
+func getHighestPointOfTrajectory(y int) int {
+	return (y * (y + 1)) / 2
+}
+
+func yy(y, t int) int {
+	return y - t
+}
+
+func xx(x, t int) int {
+	for i := 0; i < t; i++ {
+		switch {
+		case x == 0:
+			return x
+		case x > 0:
+			x--
+		case x < 0:
+			x++
+		}
+	}
+	return x
+}

2021/17/main_test.go

@@ -0,0 +1,39 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/jdrst/adventofgo/util"
+)
+
+var testInput = `target area: x=20..30, y=-10..-5`
+
+func TestPartOne(t *testing.T) {
+	expected := 45
+	actual := partOne(util.File(testInput).WithOSLinebreaks())
+	if actual != expected {
+		t.Errorf("expected was: %v \n actual is: %v", expected, actual)
+	}
+}
+
+func TestPartTwo(t *testing.T) {
+	expected := 112
+	actual := partTwo(util.File(testInput).WithOSLinebreaks())
+	if actual != expected {
+		t.Errorf("\nexpected was: %v\nactual is: %v", expected, actual)
+	}
+}
+
+func BenchmarkPartOne(b *testing.B) {
+	input := util.ReadFile("input.txt")
+	for n := 0; n < b.N; n++ {
+		partOne(input)
+	}
+}
+
+func BenchmarkPartTwo(b *testing.B) {
+	input := util.ReadFile("input.txt")
+	for n := 0; n < b.N; n++ {
+		partTwo(input)
+	}
+}

util/util.go

@@ -148,15 +148,15 @@ func (n *Point) NeighboursWithDiagonal(maxX, maxY int) []Point {
 
 //ManhattanDistance returns the manhattan distance between two points (delta between x's plus delta between y's)
 func ManhattanDistance(a, b Point) int {
-	return delta(a.X, b.X) + delta(a.Y, b.Y)
+	return Delta(a.X, b.X) + Delta(a.Y, b.Y)
 }
 
-func abs(x int) int {
+func Abs(x int) int {
 	if x < 0 {
 		return x * -1
 	}
 	return x
 }
-func delta(x, y int) int {
-	return abs(x - y)
+func Delta(x, y int) int {
+	return Abs(x - y)
 }