feat: solve day 7 part 1

cmd/07/main.go

@@ -0,0 +1,76 @@
+package main
+
+import (
+	"github.com/StevanFreeborn/advent-of-code-2025/internal/file"
+	"github.com/StevanFreeborn/advent-of-code-2025/internal/position"
+)
+
+const StartCharacter = "S"
+const SplitterCharacter = "^"
+
+func SolvePartOne(filePath string) int {
+	input := file.ReadAllLines(filePath)
+	numOfRows := len(input)
+	numOfCols := len(input[0])
+
+	startRow := -1
+	startCol := -1
+
+	for row := range numOfRows - 1 {
+		for col := range numOfCols - 1 {
+			v := string(input[row][col])
+
+			if v == StartCharacter {
+				startRow = row
+				startCol = col
+				break
+			}
+		}
+	}
+
+	if startRow < 0 || startCol < 0 {
+		panic("unable to find start location")
+	}
+
+	beamStart := position.From(startRow+1, startCol)
+	beamsQueue := []position.Position{
+		beamStart,
+	}
+	visited := map[position.Position]bool{}
+
+	total := 0
+
+	for len(beamsQueue) > 0 {
+		currentBeam := beamsQueue[0]
+		beamsQueue = beamsQueue[1:]
+
+		if visited[currentBeam] {
+			continue
+		}
+
+		if currentBeam.Row() < 0 || currentBeam.Row() >= numOfRows {
+			continue
+		}
+
+		if currentBeam.Column() < 0 || currentBeam.Column() >= numOfCols {
+			continue
+		}
+
+		visited[currentBeam] = true
+
+		value := string(input[currentBeam.Row()][currentBeam.Column()])
+
+		if value == SplitterCharacter {
+			total++
+			rightBeam := position.From(currentBeam.Row(), currentBeam.Column()+1)
+			leftBeam := position.From(currentBeam.Row(), currentBeam.Column()-1)
+			beamsQueue = append(beamsQueue, rightBeam, leftBeam)
+			continue
+		}
+
+		nextBeam := position.From(currentBeam.Row()+1, currentBeam.Column())
+		beamsQueue = append(beamsQueue, nextBeam)
+	}
+
+	return total
+}

cmd/07/main_test.go

@@ -0,0 +1,27 @@
+package main_test
+
+import (
+	"testing"
+
+	solution "github.com/StevanFreeborn/advent-of-code-2025/cmd/07"
+)
+
+func TestSolvePartOneWithExampleInput(t *testing.T) {
+	expected := 21
+
+	result := solution.SolvePartOne("EXAMPLE.txt")
+
+	if result != expected {
+		t.Errorf("SolvePartOne() = %d; want %d", result, expected)
+	}
+}
+
+func TestSolvePartOneWithInput(t *testing.T) {
+	expected := 1581
+
+	result := solution.SolvePartOne("INPUT.txt")
+
+	if result != expected {
+		t.Errorf("SolvePartOne() = %d; want %d", result, expected)
+	}
+}