Day08

2024/gareth/day08/day08.go

@@ -0,0 +1,80 @@
+package day08
+
+import (
+	"math"
+	"strings"
+)
+
+type Coordinate struct {
+	Row int
+	Col int
+}
+
+func Part1(input string) int {
+	grid, antennaMap := parseInput(input)
+	result := findAntinodes(grid, antennaMap, true)
+	return result
+}
+
+func Part2(input string) int {
+	grid, antennaMap := parseInput(input)
+	result := findAntinodes(grid, antennaMap, false)
+	return result
+}
+
+func parseInput(input string) ([][]rune, map[rune][]Coordinate) {
+	lines := strings.Split(input, "\n")
+	rowCount := len(lines)
+	colCount := len(lines[0])
+	grid := make([][]rune, rowCount)
+	antennaMap := make(map[rune][]Coordinate)
+
+	for row := 0; row < rowCount; row++ {
+		grid[row] = []rune(lines[row])
+		for col := 0; col < colCount; col++ {
+			frequency := grid[row][col]
+			if frequency != '.' {
+				antennaMap[frequency] = append(antennaMap[frequency], Coordinate{Row: row, Col: col})
+			}
+		}
+	}
+
+	return grid, antennaMap
+}
+
+func findAntinodes(grid [][]rune, antennaMap map[rune][]Coordinate, onlySpecial bool) int {
+	rowCount := len(grid)
+	colCount := len(grid[0])
+	uniqueAntinodes := make(map[Coordinate]struct{})
+
+	for row := 0; row < rowCount; row++ {
+		for col := 0; col < colCount; col++ {
+			for _, antennaPositions := range antennaMap {
+				for i, firstAntenna := range antennaPositions {
+					for j, secondAntenna := range antennaPositions {
+						//I know I know thats too many for loops
+						if i != j {
+							distance1 := int(math.Abs(float64(row-firstAntenna.Row)) + math.Abs(float64(col-firstAntenna.Col)))
+							distance2 := int(math.Abs(float64(row-secondAntenna.Row)) + math.Abs(float64(col-secondAntenna.Col)))
+
+							rowDiff1 := row - firstAntenna.Row
+							rowDiff2 := row - secondAntenna.Row
+							colDiff1 := col - firstAntenna.Col
+							colDiff2 := col - secondAntenna.Col
+
+							if rowDiff1*colDiff2 == rowDiff2*colDiff1 {
+								if (distance1 == 2*distance2 || distance1*2 == distance2) && onlySpecial {
+									uniqueAntinodes[Coordinate{Row: row, Col: col}] = struct{}{}
+								} else if !onlySpecial {
+									uniqueAntinodes[Coordinate{Row: row, Col: col}] = struct{}{}
+								}
+							}
+						}
+					}
+				}
+			}
+		}
+	}
+
+	return len(uniqueAntinodes)
+}

2024/gareth/day08/day08_test.go

@@ -0,0 +1,39 @@
+package day08
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestPart1(t *testing.T) {
+	r := Part1(`............
+........0...
+.....0......
+.......0....
+....0.......
+......A.....
+............
+............
+........A...
+.........A..
+............
+............`)
+	assert.Equal(t, 14, r)
+}
+
+func TestPart2(t *testing.T) {
+	r := Part2(`............
+........0...
+.....0......
+.......0....
+....0.......
+......A.....
+............
+............
+........A...
+.........A..
+............
+............`)
+	assert.Equal(t, 11387, r)
+}

2024/gareth/day08/input.txt

@@ -0,0 +1,50 @@
+........................E...j......W..........L...
+............................O........E.........L..
+..q......O...........l....................K.......
+............q...................HM......W.........
+................................1..H...........IW.
+....................5.............................
+..........k........M...wl............6............
+.....O.......w...k.....5.8..l......K.........o.6..
+.......k....w.........5.........R.....o........K..
+.....q..X..............j........E...I.........K...
+............O..........E........................H.
+................Mn.h2.w.p....................H....
+..................p.......a............j.....L....
+.....X...l.p.....................m.........W..6...
+..Xq................A..................R..m.......
+.........................i..........a..........R..
+...........u.....................a........I.....2.
+k..............A..n.........R.................o...
+................n.................Qo..............
+..........u.A.........h........2..................
+...5.......Y.....p...............iN...............
+1...x.....................i.......................
+........M..............2.....Qi...................
+...............................I..e...............
+......u......A...........m..........h.............
+.......1...........U.............Qm.......j.......
+.......X.......................................9..
+.....u........U.......Y...........................
+.............................h.e..................
+..................4....e......Q.....L....N........
+.1..................4.......................y8....
+.........Y................................8.N.....
+............P.0J...........3..........8y..........
+....V3P..........J................................
+............U..P...7x...........e.................
+....................J...............r...9.........
+.........0.V......Y...............................
+...............V.4................................
+..........V..........................n............
+..............v........7..........................
+...........U..........J.......7...................
+.....v........7..........................a........
+.......................................r..........
+...........0.......x................y.............
+............6..v.x.....................N..........
+...........P......................................
+........3.......................r......4..........
+..............3......................y............
+................................................9.
+.................................................9

2024/gareth/main.go

@@ -1,7 +1,7 @@
 package main
 
 import (
-	"aoc2024/day14"
+	"aoc2024/day08"
 	"fmt"
 	"os"
 	"time"
@@ -9,9 +9,9 @@ import (
 
 func main() {
 	start := time.Now()
-	data, _ := os.ReadFile("day14/input.txt")
-	fmt.Printf("part 1: %d\n", day14.Part1(string(data)))
-	fmt.Printf("part 2: %d\n", day14.Part2(string(data)))
+	data, _ := os.ReadFile("day08/input.txt")
+	fmt.Printf("part 1: %d\n", day08.Part1(string(data)))
+	fmt.Printf("part 2: %d\n", day08.Part2(string(data)))
 	elapsed := time.Since(start)
 	fmt.Printf("Execution time: %s\n", elapsed)
 }