day14p2

day14p2/solution.go

@@ -0,0 +1,101 @@
+package day14p2
+
+import (
+	"io"
+	"math"
+
+	"aoc/utils"
+)
+
+type Bot struct {
+	X, Y   int
+	VX, VY int
+}
+
+func Solve(r io.Reader) any {
+	lines := utils.ReadLines(r)
+	isTest := len(lines) == 12
+	if isTest {
+		return 0 // no test input for this one
+	}
+	boardWidth := 101
+	boardHeight := 103
+
+	bots := make([]Bot, len(lines))
+
+	for i, line := range lines {
+		ints := utils.GetInts(line)
+		px, py, vx, vy := ints[0], ints[1], ints[2], ints[3]
+		bots[i] = Bot{px, py, vx, vy}
+	}
+
+	MAX_MOVES := 10000
+
+	minDoubleOccurences := math.MaxInt
+	minStep := 0
+
+	for step := 1; step <= MAX_MOVES; step++ {
+		for i, bot := range bots {
+			bots[i].X += bot.VX
+			bots[i].Y += bot.VY
+			if bots[i].X < 0 {
+				bots[i].X += boardWidth
+			} else if bots[i].X >= boardWidth {
+				bots[i].X -= boardWidth
+			}
+			if bots[i].Y < 0 {
+				bots[i].Y += boardHeight
+			} else if bots[i].Y >= boardHeight {
+				bots[i].Y -= boardHeight
+			}
+		}
+		do := countDoubleOccurences(bots)
+		if do < minDoubleOccurences {
+			minDoubleOccurences = do
+			minStep = step
+		}
+		if minDoubleOccurences <= 1 {
+			break
+		}
+	}
+
+	return minStep
+}
+
+func countDoubleOccurences(bots []Bot) int {
+	occurences := make(map[utils.Point]int)
+
+	for _, bot := range bots {
+		occurences[utils.Point{X: bot.X, Y: bot.Y}]++
+	}
+
+	doubleOccurences := 0
+	for _, count := range occurences {
+		if count > 1 {
+			doubleOccurences++
+		}
+	}
+
+	return doubleOccurences
+}
+
+func printBoard(bots []Bot, boardWidth, boardHeight int) {
+	board := make([][]rune, boardHeight)
+	for i := range board {
+		board[i] = make([]rune, boardWidth)
+		for j := range board[i] {
+			board[i][j] = '.'
+		}
+	}
+
+	for _, bot := range bots {
+		board[bot.Y][bot.X] = '#'
+	}
+
+	for _, row := range board {
+		for _, r := range row {
+			print(string(r))
+		}
+		println()
+	}
+}

day14p2/solution_test.go

@@ -0,0 +1,44 @@
+package day14p2
+
+import (
+	"strings"
+	"testing"
+
+	"aoc/utils"
+)
+
+var testInput = `p=0,4 v=3,-3
+p=6,3 v=-1,-3
+p=10,3 v=-1,2
+p=2,0 v=2,-1
+p=0,0 v=1,3
+p=3,0 v=-2,-2
+p=7,6 v=-1,-3
+p=3,0 v=-1,-2
+p=9,3 v=2,3
+p=7,3 v=-1,2
+p=2,4 v=2,-3
+p=9,5 v=-3,-3`
+
+func TestSolve(t *testing.T) {
+	tests := []struct {
+		input  string
+		answer int
+	}{
+		{testInput, 0},
+	}
+
+	if testing.Verbose() {
+		utils.Verbose = true
+	}
+
+	for _, test := range tests {
+		r := strings.NewReader(test.input)
+
+		result := Solve(r).(int)
+
+		if result != test.answer {
+			t.Errorf("Expected %d, got %d", test.answer, result)
+		}
+	}
+}