2022 Day 15 Complete!

2022/day15/main.go

@@ -5,7 +5,6 @@ import (
 	"math"
 	"os"
 	"strings"
-	"time"
 
 	h "git.bullercodeworks.com/brian/adventofcode/helpers"
 )
@@ -79,122 +78,32 @@ func part1(inp []string) {
 	fmt.Println(nopeCount)
 }
 
-type Sensor struct {
-	c h.Coordinate // Sensor Position
-	b h.Coordinate // Beacon Position
-	d int          // Distance
-}
-
-func (s Sensor) isInRange(c h.Coordinate) bool { return s.c.Distance(c) <= s.d }
-
-func (s Sensor) String() string { return s.c.String() }
-
 func part2(inp []string) {
-	var sensors []Sensor
+	var spots [][]int
 	for i := range inp {
-		s := Sensor{}
-		s.c, s.b = strToCoords(inp[i])
-		s.d = s.c.Distance(s.b)
-		sensors = append(sensors, s)
+		s, b := strToCoords(inp[i])
+		xs, ys, xb, yb := s.X, s.Y, b.X, b.Y
+		dist := s.Distance(b)
+		spots = append(spots, []int{xs, ys, xb, yb, dist})
 	}
-
-	max := testRow * 2
-	found := []h.Coordinate{}
-	// Check around each sensor, the beacon must be it's distance + 1
-	for _, sensor := range sensors {
-		d := sensor.d + 1
-		testEnds := []h.Coordinate{
-			{X: sensor.c.X, Y: sensor.c.Y - d},
-			{X: sensor.c.X + d, Y: sensor.c.Y},
-			{X: sensor.c.X, Y: sensor.c.Y + d},
-			{X: sensor.c.X - d, Y: sensor.c.Y},
-		}
-		printMap(sensors, max, max, h.Coordinate{X: math.MinInt, Y: math.MinInt})
-		var tstX, tstY int
-		for i := 0; i < 3; i++ {
-			// Test all spots between testEnds[i] & testEnds[i+1]
-			for tstX != testEnds[i+1].X && tstY != testEnds[i+1].Y {
-				if testEnds[i].X < testEnds[i+1].X {
-					tstX++
-					if testEnds[i].Y < testEnds[i+1].Y {
-						tstY++
-					} else {
-						tstY--
-					}
-				} else {
-					tstX--
-					if testEnds[i].Y < testEnds[i+1].Y {
-						tstY++
-					} else {
-						tstY--
-					}
-				}
-			}
-			if tstX <= max && tstY <= max {
-				fmt.Print(h.CLEAR_SCREEN)
-				printMap(sensors, max, max, h.Coordinate{X: tstX, Y: tstY})
-				fmt.Println("Testing", tstX, ",", tstY)
-				time.Sleep(time.Second / 10)
-				if testSpot(tstX, tstY, sensors) {
-					found = append(found, h.Coordinate{X: tstX, Y: tstY})
+	min, max := 0, testRow*2
+	// Brute-force it
+	for y := min; y <= max; y++ {
+	SEARCH:
+		for x := min; x <= max; x++ {
+			for _, c := range spots {
+				if dx, dy := c[0]-x, c[1]-y; h.Abs(dx)+h.Abs(dy) <= c[4] {
+					// Jump across the sensor's scan area
+					x += c[4] - h.Abs(dy) + dx
+					continue SEARCH
 				}
 			}
+			// If we get here, we found it.
+			fmt.Println("# Part 2")
+			fmt.Println(x*4000000 + y)
+			return
 		}
 	}
-
-	fmt.Println("# Part 2")
-	fmt.Println(found)
-	//fmt.Println((found.X * 4000000) + found.Y)
-}
-
-func testSpot(x, y int, sensors []Sensor) bool {
-	var wasInRange bool
-	for i := range sensors {
-		if sensors[i].isInRange(h.Coordinate{X: x, Y: y}) {
-			wasInRange = true
-			break
-		}
-	}
-	return !wasInRange
-}
-
-func printMap(sensors []Sensor, ceilX, ceilY int, tstPos h.Coordinate) {
-	minX, maxX, minY, maxY := math.MaxInt, math.MinInt, math.MaxInt, math.MinInt
-	for i := range sensors {
-		minX = h.Min(sensors[i].b.X, minX)
-		maxX = h.Max(sensors[i].b.X, maxX)
-		minY = h.Min(sensors[i].b.Y, minY)
-		maxY = h.Max(sensors[i].b.Y, maxY)
-	}
-	for y := minY; y <= maxY; y++ {
-		for x := minX; x <= maxX; x++ {
-			wrk := h.Coordinate{X: x, Y: y}
-			var found bool
-			for _, sensor := range sensors {
-				if sensor.c.Equals(wrk) {
-					fmt.Print("S")
-					found = true
-					break
-				} else if sensor.b.Equals(wrk) {
-					fmt.Print("B")
-					found = true
-					break
-				} else if sensor.isInRange(wrk) {
-					fmt.Print("#")
-					found = true
-					break
-				}
-			}
-			if !found {
-				if wrk.Equals(tstPos) {
-					fmt.Print(h.FILL_CHAR)
-				} else {
-					fmt.Print(".")
-				}
-			}
-		}
-		fmt.Println()
-	}
 }
 
 func strToCoords(s string) (h.Coordinate, h.Coordinate) {