Day 19 functional

We're at about 1s runtime on my macbook, but we do get the right answer now.

days/19.go

@@ -61,120 +61,62 @@ func (d *Day19) Part1() string {
 }
 
 func (d *Day19) Part2() string {
-	grid := make([][]bool, 5000)
-	for y := 0; y < len(grid); y++ {
-		grid[y] = make([]bool, 5000)
+	f := func(x, y int) bool {
+		ret := false
+		d.program.Reset()
+		d.program.RunIn(func(inputStep int) int64 {
+			if inputStep == 1 {
+				return int64(x)
+			}
+			return int64(y)
+		}, func(val int64, state u.IntcodeProgramState) {
+			ret = val == 1
+		})
+
+		return ret
 	}
 
-	// find first hit
-	firstY := 0
-	for y := 1; firstY == 0; y++ {
+	// find lower bound
+	startY := 0
+	startX := 0
+	for y := 1; startY == 0; y++ {
 		for x := 0; x < 10*y; x++ {
-			d.program.Reset()
-			d.program.RunIn(func(inputStep int) int64 {
-				if inputStep == 1 {
-					return int64(x)
-				}
-				return int64(y)
-			}, func(val int64, state u.IntcodeProgramState) {
-				if val == 1 {
-					if firstY == 0 {
-						firstY = y
-						d.program.Stop()
-					}
-				}
-			})
+			if f(x, y) {
+				startY = y
+				startX = x
+				break
+			}
 		}
 	}
 
 	done := false
-	y := firstY
-	x := 0
-	firstFoundX := 0
-	firstFoundY := 0
-	lastX := 0
-	lastY := 0
-	for y = firstY; !done; y++ {
-		lastFoundX := -1
-		for x = firstFoundX; lastFoundX == -1 || lastFoundX == x-1; x++ {
-			d.program.Reset()
-			d.program.RunIn(func(inputStep int) int64 {
-				if inputStep == 1 {
-					return int64(x)
-				}
-
-				return int64(y)
-			}, func(val int64, state u.IntcodeProgramState) {
-				res := val == 1
-				grid[y][x] = res
-				if res {
-					if lastFoundX == -1 {
-						firstFoundX = x
-					}
-					lastFoundX = x
-				}
-			})
-		}
-
-		if lastFoundX-firstFoundX+1 >= 100 {
-			if firstFoundY == 0 {
-				firstFoundY = y
-			}
-			done = grid[y-100][firstFoundX+100]
-			if done {
-				for checkY := y - 100; checkY <= y; checkY++ {
-					if !grid[checkY][firstFoundX+100] || !grid[checkY][firstFoundX] {
-						done = false
-						break
-					}
-				}
-
-				if done {
-					lastX = firstFoundX + 100
-					lastY = y
+	for y := startY; !done; y++ {
+		foundX := false
+		for x := startX; ; x++ {
+			if !f(x, y) {
+				if !foundX {
+					continue
+				} else {
+					break
 				}
 			}
-		}
+			if !foundX {
+				foundX = true
+				startX = x
+			}
 
-		// if lastFoundX-firstFoundX+1 >= 100 {
-		// 	fmt.Printf("At y=%d, x reached %d for %d in a row\n", y, lastFoundX, lastFoundX-firstFoundX+1)
-		// }
-	}
-
-	for y := firstFoundY; y <= lastY; y++ {
-		for x = 0; ; x++ {
-			if grid[y][x] {
+			if !f(x+99, y) {
 				break
 			}
-		}
-
-		found := true
-		for y2 := y + 1; y2 < y+100; y2++ {
-			if !grid[y2][x] {
-				found = false
-				break
+			if !f(x, y+99) {
+				continue
 			}
-		}
 
-		if found {
-			fmt.Printf("100 down, 100 across starts at y=%d, x=%d\n", y, x)
+			fmt.Printf("x=%d, y=%d, so result=%d\n", x, y, (x*10000)+y)
+			done = true
+			break
 		}
 	}
 
-	// fmt.Println("part 2 tractor view:")
-	// for y := 0; y < len(grid); y++ {
-	// 	for x := 0; x < len(grid[y]); x++ {
-	// 		if grid[y][x] {
-	// 			fmt.Print("█")
-	// 		} else {
-	// 			fmt.Print(" ")
-	// 		}
-	// 	}
-	// 	fmt.Println()
-	// }
-
-	origX := lastX - 100
-	origY := lastY - 100
-	result := (origX * 10000) + origY
-	return fmt.Sprintf("x=%d, y=%d, orig x=%d, orig y=%d, %s%d%s", lastX, lastY, origX, origY, u.TextBold, result, u.TextReset)
+	return "0"
 }