2024 day 8 part 1

2024/go/inputs/day8/example.txt

@@ -0,0 +1,10 @@
+..........
+..........
+..........
+..........
+..........
+..........
+..........
+..........
+........a.
+........a.

2024/go/inputs/day8/example2.txt

@@ -0,0 +1,12 @@
+............
+........0...
+.....0......
+.......0....
+....0.......
+......A.....
+............
+............
+........A...
+.........A..
+............
+............

2024/go/inputs/day8/input.txt

@@ -0,0 +1,50 @@
+..................................w...............
+..................................................
+.....................................C............
+......................................3...........
+.............b.......u.........w...........3......
+...........................u......................
+...8........K...........u.......y.........I.......
+..................................P5........B.....
+...U................2.P...............B...C.......
+............i......x.P........w......s.C......IB5.
+..............t....................y....x.........
+.......8............K....1.......w............u...
+.................i.............r.........s........
+..2.............t..T.K.......r......8..........I..
+8..............t..T.....r...................5.....
+...2........................1....M.t...N....x.....
+...V....U.......................N.S..........I....
+.........W...i............O....v............S.....
+................L...1...s.fT.....x............3...
+....6.......C...N.........Tf.3....................
+...6.......F..........V..........k...N......H.....
+...................U..f........0......H.y.........
+.......................O...P......0...............
+.......L..U....m.......R............s.............
+6...i.................O....0.2.........H.....B....
+........................R......H.........S........
+......F.....c..........m..............d...........
+................F.L.....m..................7......
+.............J.........................S..........
+.b....j.k..............V0.........................
+.................L.....K..........................
+.......F.......J..............r.....M.............
+......................m1....a.R...7...............
+.......4......Y..6.D..............................
+k............9.......D................M...........
+.....Xb.................V...h.....................
+A.........9.Xl..........D......R..................
+4.............c..d........D.............7.........
+.A.4.............c.............M.7.v..............
+..........n.9........................h............
+...j....bd.........f.....p..W.....................
+.............k.........p..........................
+.......W4.......p......X.....5..J.....v...........
+........W.d..c......A........n..v.....o...........
+..........l.....n..........o......Y...h...........
+.....A............................................
+..j..........n....................................
+a9.lX..................Y...........o..............
+.......a.................Y..........o.............
+...a....l.......................p.................

2024/go/pkg/day8/day8.go

@@ -0,0 +1,18 @@
+package day8
+
+import (
+	"errors"
+	"fmt"
+	"os"
+)
+
+func Execute(part string, file *os.File) (int, error) {
+	switch part {
+	case "1":
+		return Part1(file), nil
+	case "2":
+		return Part2(file), nil
+	default:
+		return 0, errors.New(fmt.Sprintf("unknown part: %s", part))
+	}
+}

2024/go/pkg/day8/part1.go

@@ -0,0 +1,74 @@
+package day8
+
+import (
+	"os"
+	"strings"
+
+	"github.com/timredband/advent-of-code/pkg/utils"
+)
+
+type Coordinate struct {
+	x int
+	y int
+}
+
+func Part1(file *os.File) int {
+	inputs := utils.ReadFile(file)
+	board := make([][]string, len(inputs))
+
+	for i, v := range inputs {
+		line := strings.Split(v, "")
+		board[i] = line
+	}
+
+	coordinatesByAntenna := make(map[string][]Coordinate)
+
+	for x, row := range board {
+		for y, val := range row {
+			if val == "." {
+				continue
+			}
+
+			if _, ok := coordinatesByAntenna[val]; !ok {
+				coordinatesByAntenna[val] = make([]Coordinate, 0)
+			}
+
+			coordinatesByAntenna[val] = append(coordinatesByAntenna[val], Coordinate{x, y})
+		}
+
+	}
+
+	antinodeCoordinates := make(map[Coordinate]struct{})
+
+	for _, coordinates := range coordinatesByAntenna {
+		i, j := 0, 1
+
+		for i < len(coordinates) {
+			for j < len(coordinates) {
+				xDiff := coordinates[i].x - coordinates[j].x
+				yDiff := coordinates[i].y - coordinates[j].y
+
+				firstAntiNode := Coordinate{x: coordinates[i].x + xDiff, y: coordinates[i].y + yDiff}
+				secondAntiNode := Coordinate{x: coordinates[j].x - xDiff, y: coordinates[j].y - yDiff}
+
+				if firstAntiNode.x >= 0 && firstAntiNode.x < len(board) && firstAntiNode.y >= 0 && firstAntiNode.y < len(board) {
+					antinodeCoordinates[firstAntiNode] = struct{}{}
+				}
+
+				if secondAntiNode.x >= 0 && secondAntiNode.x < len(board) && secondAntiNode.y >= 0 && secondAntiNode.y < len(board) {
+					antinodeCoordinates[secondAntiNode] = struct{}{}
+				}
+
+				j += 1
+			}
+
+			coordinates = coordinates[1:]
+
+			i, j = 0, 1
+		}
+	}
+
+	result := len(antinodeCoordinates)
+
+	return result
+}

2024/go/pkg/day8/part2.go

@@ -0,0 +1,9 @@
+package day8
+
+import (
+	"os"
+)
+
+func Part2(file *os.File) int {
+	return 0
+}

2024/go/pkg/days/days.go

@@ -12,6 +12,7 @@ import (
 	"github.com/timredband/advent-of-code/pkg/day5"
 	"github.com/timredband/advent-of-code/pkg/day6"
 	"github.com/timredband/advent-of-code/pkg/day7"
+	"github.com/timredband/advent-of-code/pkg/day8"
 )
 
 func Execute(day string, part string, file *os.File) (int, error) {
@@ -30,6 +31,8 @@ func Execute(day string, part string, file *os.File) (int, error) {
 		return day6.Execute(part, file)
 	case "7":
 		return day7.Execute(part, file)
+	case "8":
+		return day8.Execute(part, file)
 	default:
 		return 0, errors.New(fmt.Sprintf("unknown day: %s", day))
 	}