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)
+}