2024 Day 14 Complete!

2024/day14/main.go

@@ -0,0 +1,164 @@
+package main
+
+import (
+	"fmt"
+	"math"
+
+	h "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+func main() {
+	inp := h.StdinToStringSlice()
+	part1(inp)
+	fmt.Println()
+	part2(inp)
+}
+
+func part1(inp []string) {
+	fmt.Println("# Part 1")
+	// Main Input size
+	sizeX, sizeY := 101, 103
+	bots := parseInput(inp, sizeX, sizeY)
+	for i := 0; i < 100; i++ {
+		for j := range bots {
+			bots[j].Move()
+		}
+	}
+	for i := range bots {
+		fmt.Println(bots[i])
+	}
+	qCnt := make([]int, 4)
+	for y := 0; y < sizeY; y++ {
+		for x := 0; x < sizeX; x++ {
+			if x == sizeX/2 || y == sizeY/2 {
+				fmt.Print(" ")
+				continue
+			}
+			bCnt := 0
+			for i := range bots {
+				if x == bots[i].X && y == bots[i].Y {
+					bCnt++
+					if x < sizeX/2 {
+						if y < sizeY/2 {
+							qCnt[0]++
+						} else {
+							qCnt[2]++
+						}
+					} else {
+						if y < sizeY/2 {
+							qCnt[1]++
+						} else {
+							qCnt[3]++
+						}
+					}
+				}
+			}
+			if bCnt > 0 {
+				fmt.Print(bCnt)
+			} else {
+				fmt.Print(".")
+			}
+		}
+		fmt.Println()
+	}
+	fmt.Println("Safety Factor:", (qCnt[0] * qCnt[1] * qCnt[2] * qCnt[3]))
+}
+
+func part2(inp []string) {
+	fmt.Println("# Part 2")
+	// Main Input size
+	sizeX, sizeY := 101, 103
+	bots := parseInput(inp, sizeX, sizeY)
+	printState := func() {
+		for y := 0; y < sizeY; y++ {
+			for x := 0; x < sizeX; x++ {
+				btCnt := 0
+				for _, b := range bots {
+					if b.X == x && b.Y == y {
+						btCnt++
+					}
+				}
+				if btCnt == 0 {
+					fmt.Print(".")
+				} else if btCnt < 10 {
+					fmt.Print(btCnt)
+				} else {
+					fmt.Print("#")
+				}
+			}
+			fmt.Println()
+		}
+	}
+	// My hypothesis: most bots will be close to each other for the answer
+	lowest := h.MAX_INT
+	var lowStdX, lowStdY float64
+	for steps := 0; steps < 10000000; steps++ {
+		xs := make([]int, 0, len(bots))
+		ys := make([]int, 0, len(bots))
+		for j := range bots {
+			bots[j].Move()
+			xs = append(xs, bots[j].X)
+			ys = append(ys, bots[j].Y)
+		}
+		// After finding it, I added this to print it out :D
+		if steps == 7036 {
+			printState()
+		}
+		wrkX, wrkY := stdev(xs), stdev(ys)
+		if lowest == h.MAX_INT || (wrkX < lowStdX && wrkY < lowStdY) {
+			fmt.Println(lowest, ":", lowStdX, lowStdY)
+			lowStdX, lowStdY, lowest = wrkX, wrkY, steps
+		}
+	}
+	fmt.Println("Steps to Easter Egg:", lowest)
+}
+
+func stdev(vals []int) float64 {
+	m := 0.0
+	for _, w := range vals {
+		m += float64(w)
+	}
+	m /= float64(len(vals))
+	v := 0.0
+	for _, w := range vals {
+		diff := float64(w) - m
+		v += diff * diff
+	}
+	return math.Sqrt(v / float64(len(vals)))
+}
+
+var botRaw = "p=%d,%d v=%d,%d"
+
+type Bot struct {
+	X, Y, Vx, Vy int
+	mX, mY       int
+}
+
+func NewBot(inp string) *Bot {
+	b := Bot{}
+	fmt.Sscanf(inp, botRaw, &b.X, &b.Y, &b.Vx, &b.Vy)
+	return &b
+}
+
+func (b *Bot) Move() {
+	b.X = (b.X + b.Vx + b.mX) % b.mX
+	b.Y = (b.Y + b.Vy + b.mY) % b.mY
+}
+
+func (b *Bot) Overlaps(bt *Bot) bool {
+	return b.X == bt.X && b.Y == bt.Y
+}
+
+func (b Bot) String() string {
+	return fmt.Sprintf(botRaw, b.X, b.Y, b.Vx, b.Vy)
+}
+
+func parseInput(inp []string, mX, mY int) []*Bot {
+	var ret []*Bot
+	for i := range inp {
+		b := NewBot(inp[i])
+		b.mX, b.mY = mX, mY
+		ret = append(ret, b)
+	}
+	return ret
+}