d5p2

d5/d5.go

@@ -56,6 +56,41 @@ func generatePoints(segments []segment) []point {
 	return points
 }
 
+func generatePointsWithDiagonals(segments []segment) []point {
+	points := []point{}
+
+	for _, segment := range segments {
+		startX := segment.a.x
+		startY := segment.a.y
+		endX := segment.b.x
+		endY := segment.b.y
+
+		dx := 1
+		dy := 1
+
+		if segment.a.x == segment.b.x {
+			dx = 0
+		} else if segment.a.x > segment.b.x {
+			dx = -1
+		}
+
+		if segment.a.y == segment.b.y {
+			dy = 0
+		} else if segment.a.y > segment.b.y {
+			dy = -1
+		}
+
+		points = append(points, point{startX, startY})
+		for startX != endX || startY != endY {
+			startX += dx
+			startY += dy
+			points = append(points, point{startX, startY})
+		}
+	}
+
+	return points
+}
+
 func findIntersections(points []point) map[point]int {
 
 	intersections := map[point]int{}
@@ -86,3 +121,11 @@ func D5(input string) int {
 	intersections := findIntersections(points)
 	return countIntersections(intersections)
 }
+
+func D5P2(input string) int {
+	lines := strings.Split(strings.TrimSpace(input), "\n")
+	segments := createSegments(lines)
+	points := generatePointsWithDiagonals(segments)
+	intersections := findIntersections(points)
+	return countIntersections(intersections)
+}

d5/d5_test.go

@@ -20,3 +20,18 @@ func TestD5(t *testing.T) {
 
 	assert.EqualValues(t, 5, D5(input))
 }
+
+func TestD5P2(t *testing.T) {
+	input := `0,9 -> 5,9
+8,0 -> 0,8
+9,4 -> 3,4
+2,2 -> 2,1
+7,0 -> 7,4
+6,4 -> 2,0
+0,9 -> 2,9
+3,4 -> 1,4
+0,0 -> 8,8
+5,5 -> 8,2`
+
+	assert.EqualValues(t, 12, D5P2(input))
+}

main.go

@@ -33,4 +33,5 @@ func main() {
 	fmt.Printf("day 4: %v\n", d4.D4(client.Day(4)))
 	fmt.Printf("day 4 part 2: %v\n", d4.D4P2(client.Day(4)))
 	fmt.Printf("day 5: %v\n", d5.D5(client.Day(5)))
+	fmt.Printf("day 5 part 2: %v\n", d5.D5P2(client.Day(5)))
 }