Add solution for day 8 part 1

Author: terminalnode

README.md

@@ -52,7 +52,7 @@ automatically rebuilt and redeployed ever time the `common` module or their own
 | 05  | ⭐ ⭐      | 18  |          |
 | 06  | ⭐ ⭐      | 19  |          |
 | 07  | ⭐ ⭐      | 20  |          |
-| 08  |          | 21  |          |
+| 08  | ⭐        | 21  |          |
 | 09  |          | 22  |          |
 | 10  |          | 23  |          |
 | 11  |          | 24  |          |

solutions/day08/main.go

@@ -1,9 +1,53 @@
 package main
 
 import (
+	"fmt"
 	"github.com/terminalnode/adventofcode2024/common"
+	"github.com/terminalnode/adventofcode2024/common/util"
 )
 
 func main() {
-	common.Setup(8, nil, nil)
+	common.Setup(8, part1, nil)
+}
+
+func part1(
+	input string,
+) string {
+	m, err := util.NewCharMatrix(input)
+	if err != nil {
+		return fmt.Sprintf("Failed to parse input: %v", err)
+	}
+
+	coords := make(map[uint8][]util.Coordinate)
+	for x := 0; x <= m.MaxX; x++ {
+		for y := 0; y <= m.MaxY; y++ {
+			char, _ := m.Get(x, y)
+			if char == '.' {
+				continue
+			}
+			coords[char] = append(coords[char], util.Coordinate{X: x, Y: y})
+		}
+	}
+
+	antiNodeSet := make(map[string]bool)
+	for c, charCoords := range coords {
+		for i, thisCoord := range charCoords {
+			for _, otherCoord := range charCoords[i+1:] {
+				xDiff := thisCoord.X - otherCoord.X
+				yDiff := thisCoord.Y - otherCoord.Y
+				antiNodes := []util.Coordinate{
+					{X: thisCoord.X + xDiff, Y: thisCoord.Y + yDiff},
+					{X: otherCoord.X - xDiff, Y: otherCoord.Y - yDiff},
+				}
+				for _, antiNode := range antiNodes {
+					if m.IsInMatrix(antiNode.X, antiNode.Y) {
+						key := fmt.Sprintf("%d,%d", antiNode.X, antiNode.Y)
+						antiNodeSet[key] = true
+					}
+				}
+			}
+		}
+	}
+
+	return fmt.Sprintf("Unique anti nodes: %d", len(antiNodeSet))
 }