Solutions for Day Eleven

day11/input.txt

@@ -0,0 +1,98 @@
+LLLLLLLLLL.LLLLLLLL.LLLLLLLLLLLLL.LLLLL.LLLL.LL.L.LLLLLLLLLLLLLLLLLLLLLLLLLL.LLLLLLLLLLLLLL
+LLLLLLLLLL.LLLLLL.L.LLLLLLL.LLLLL.LLLLL.LLLL.LLLLLLLLLLLLL..LLLLLLLLLLLLLLLL.LLLLL.LLLLLLLL
+LLLLLLLLLLLLLLLLLLLLLLLLLLL..L.LLLLLLLLLLLLLLL.LL.LLLLLLLLL.LLLLLLLLL.LLLLLL.LLLLLLLL.LLLLL
+LLLLLLLLLL.LL..LLLL.LLLLLLL.LLLLLLLLLLL.LLLLLLLLLLL.LLLLLLLLLLLLLLLLL.LLLLLL.LLLLL.LLLLLLLL
+LLLLLLLLLL.LLLLLLLL.LLLLLLL.LLLLLLLLLLLLLLLL.LLLLLLLLLLLLLLLLLLLLLLLL.LLLLLL.LLLL..LLLLLLLL
+LL.L..L.L..L.LL..L.....LLLL..L.L.LL..L...LLLLLL...L.....L.....LL.L...LLLLL..L.LL..L..L.LL..
+LLLLLLLLLL.LLLLLLLL.LLLLLLLL.LLLL.LLLLL.LLLL.LLLLLLLLLLLLLL.LLLLLLLLLLLLLLLL.LLLLLLLLLLLLLL
+LLLLLLLLLL..LLLLLLL.LLLLLLL.LLLLL.L.LLL.LLLL.LLLL.LLLLLLLLL.LLLLLLLLL.LLLLLL.LLLLLLLLLLLLLL
+L.LLLLLLLLLL.LLL..LLLLLLLLL.LLLLL.LLLLL..LLLLLLLL.LLLLLLLLL.LLLLLLLLL.LLLLLL.LLLL..LLLLLLLL
+LLLLLLLLLL.LLLLLLLLLLLLLLL..LLLLLLLLLLL.L.LL.LLLL.LLLLLLLLL.LLLLLLLLL.LLLLLL.LLLLL.LLLLLLLL
+LLLLLLLL.L.LLLLLLLLLLLLLLLL.LLLLLLLLLLL.LLLLLLLLL.LLLLLLLLL.LLLLLLLLLLLLLLLL.LLLLLLLL.LLLLL
+.......LL.L....L......L....L...L.LL..L..L...L.LL.L.LL..L..L.L.LLL.....L...LL..L..L..L.LL..L
+LLL.LLLLLLLLLLLLLLL.LLLLLLL.LLLLL.LLLLL.L.LL.LLLLLLLLLL.LLLLLLLLLLLLLLLLLLLL.LLLLL.LLLLLLLL
+LLLLLLLLLL.LLLLLLLL.LLL.LLL.LLLLL.LLLLL.LLLL.LLLLLLLLLLLLLLLLLLLLLLLLLLLLLL..LLLLLLLLLLLLLL
+LLLLLLLLLLLLLLLLLLL.LLLLLLL.LLLLL.LLLLL.LLLLLLLLL.LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL.LLLLLLLL
+LLLLLLL.LL.LLLL.LLL..LLLLLL.LLLLL.LLLLLLLLLL.LLLL.LLLLLLLLL.LLLL.LLLL.LLLLLL.LLLLL.LLLLLLLL
+LLLLLLLLLL.LL.LLLLL.LLLLLLLLLLLLL.LLLLL.LLLL.LLLL.LLLLLLLLL.LLLLLLLLL.LLLLLLL.LLLL.LLLL.LLL
+LLLLLLLLLL.LLLLLLLLLLLLLLLL.LLLLL.LLLLL.LLLLLLLLL.LLLLLLLLL.LLLLLLLLL.LLLLLLLLLLLL.LLLLLLLL
+.LL..LL.L.L....L...L.........L......LL.L..........L....L...L.L..L.L.L.LLL...LLL.L.....L.L..
+LLLLLLLLLL.LLLLLLLLLLLLLLLL.LLLLL.LLLLL.LLLLLLLLL.LLLL.LLLL.LLLLLLLLLLLLLLLLLLLLLL.LLLLLLLL
+LLLLLLLLLLLLLLLLL.L.LLL.LLL.LLLLL.LLLLL.LLLL.LLLLLLLLLLLLLL.LLLLLLLLL..LLLLL.LLLLL.LLLLLLLL
+LL.LLLLLLL.LL.LLLLL.LLLLLLL.LLLLLLLLLLLLLLLL..LLL.LLL.LLLLL.LLLLLLLL..LLLLLL.LLLLL.LLLLLLLL
+LLLLLLLLLL.LLLLLLLL.LLLLLLL.LLLLLLLLLLLLLLLL.LLLLLLL.LL..LL.LLLLLLLLL.LLLLLL.LLLLL.LLLLLLLL
+LLLLLLLLLL.LLLLLLLL.LLLLL.L.LLLLLLLL.LL.LLLL.LLLL.LLLLLLLLL.LLL.LLLLL.L.LLLL.LLLLL.LLLLLLLL
+LL.LLLLLLL.LLLLLLLL.LLLLLLLLLLLLL.LL.LLLLLLL.LLLL..LLLLLLLLLLLLLLLL.LLLLLLLLLLLLLL.LLLLLLLL
+......L.L......L.L.LLL.L.......L.LL..L..........LLL.LL..L.L............LL.LL.L.LL.......L..
+LLLLLLLLLL.LLLLLLLLLLLLLLLL.LLLLLL.LLLLLLLLLLLLLLLLLLLLLLLL.LLLLLLLLLL.LLLLL.LLLLLLLLLLLLLL
+LLLLLLLLLLLL.LLLLLL.LLLLLLLLLLLLL.L.LLL.LLLLL.LLL.LLLLLLLLL.LLLLLLLLL.LLLLLLLLLLLLLLLLLLLLL
+LLLLLLLLLL.LLLLLLLLLLLLLLLL.LLLLL.LLLLL.LLLLLLLLL.LLLLLLLLL.LLLLLLLLL..LLLLLLLLLLLLLLLLLLLL
+LLLLLLLLLLLLLLLLLLL.LLLLLLL.L.LLL.LLLLLLLLLL.LLLL.LLLLLLLLLLLLLLLLLLL.LLLLLLLLLLLL.LLLLLLLL
+LLLLLLLLLL.LLLLLLLLLLLLLLLL.LLLLL.LLLLL.LLLL.LLLL.LLLLLLLLL.LLLLLLLLLLLLLLLL.LLLLL.LLLLLLLL
+LLLLL.LLLL.LLLL.LLLLLLLLLLL.LLLLL.LLLLL.LLLL..LL..LLLLLLLLL.LLLLLLLLLLLLLLLL.LLLLLLLLLLL.LL
+LL.LLLLLLLLLLLLLLLL.LLL.LLL.LLLLL.L.LLL.LLLLLLLLLLLLLLLLLLL.LLLLLLLLL.L.LLLLLLLLLLLLLLLLLLL
+LLLLLL.LLLLLLLLLLLLLLLLLLLLLLLLLL.LLLLLLLLLL.LLLL.LLLLLLLLLLLLLLLLLL..LLLLLLLLL..L.LLLLLLLL
+........LL.........L........L.L.LL..L.......L....L.....L.......L...L.L..L..........L......L
+LL.LLLLLLL.LLLLLLLL.LLLLLL.LLL.LLLLLLLL.LLLL.LLLLLLLLLLLLLL.LLLLLLLLL.LLLLLLLLLLLL.LLLLLLLL
+LLLLLLLLLL.LLLLLLLLLL.LLLLLLLLLLL.LLLLL.LLLL.LLLL.LLLLLLLLLLLLLLL.LLL.LLLLLL.LLLLL.LLLLLL.L
+LLLLLLLLLL.LLLLLLLLLLLLLLLL..LLLLLLLLLL.LLLLLLLLLLLLLLLLLLL.LLLLLLLLL.LLLLLLLLLLLLLLLLLLLLL
+LLLLLLLLLL.LLL.LLLLLLLLLLLL.LLLLL.LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL.LLLLLL.LLLLLLLLLLLLLL
+LLLLLLLLLL.LLLLLLLLLLLLLLLL.LLLLLLLLLLL.LLLL.LL.L.LLLLLLLLL.LLLLLLLLLLLLLLLLLLLLLL.LLLLLLLL
+LLLLLLLLLLLLLLLLLLL.LLLLL.LLLLLLL.LLL.L.LLLL.LLLL.LLLLLLLLLLLLLLLLLLLLLLLLLL.LLLLL.LLLLLLLL
+...L....L.LL..L.......L..L...L.LL..LL.L....LL......L...L..L.....LL.LL....L.L..L.....L..L.L.
+LLLLLLLLLLLLLLLLLLLLLLLL.LL.LLLLL.LLLLL.LLLL.LLLL.LLLLLLLLL.LLLLLLLLLLLLLLL..LLLLL.LLLLLLLL
+LLLLLLLLLL.LLLLLLLL.LLLLLLL.LLLLL.LLLLL.LLLLLLLLL.LLLLLLLLLLLLLLLLLLL.LLLLLL.LLLLLLLLLLLLLL
+LLLLLLLLLL.LLLLLLLLLLLLLLLLLLLLLL.LLLLLLLLLLLLLLL.LLLLL.LLL.LLLLLLLLL.LLL.LL.LLLLL.LLLLLLLL
+LLLLLLLLLL.LLLLLLLLLLLLLLLLLLLLLL.LLLLLLLLLLLLLLLLLLLLLLLLL.LLLLLLLLL.LLLLLL.LLLLL.LLLLLLLL
+LLLLLLLLLL.LLL.LLLLLLLLLLLL.LLLLL.LLLLL.LLLLLLLLL.LLLLLLLLL.LLLLLLLLL.LLLLLLLLLLLL.LLL.LLLL
+L.L..LL..L..LL....L...LL...L.LL...L.L.......LL.......L.LLL....L.....L..L.L..L...L.L.L.L....
+LLLLLLLLLL.LLLLLLLLLL.LLLLL.LLLLL.LLLLLLLLLLLLLLLLLLLLLLLLL.LLLLLLLLLLLLLLLL.LLLLL.LLLLLLLL
+LLLLLLLLLL.LLLLLLLL.LL.LLLLLLLLL.LLLLLL.LLLL.LLLL.LLLLLLLLL.LLLLLLLLL.LLLLLLLLLLLL.LLLLLLLL
+LLLLLLLLLL.LLLLLLLL.LLLLLLL.LLLLL.LLLLL.LLLL.LLLL.LLLLLLLLLLLLLLLLLLL.LLLLLL.LLLLLLLLL.LLLL
+LLLLLLLLLL.LLLLLLLL.LLLLLLLLLLLLL.LLLLL.LLLLLLLLLLLLLLLLLLL.LLLLLLLLL.LLLLLL.LLL.L.LLLLL.LL
+LLLLLLLLLLLLLL.LLLL..LLLLLL.LLLLL.LLLLL.LLLL.LLLLLLLLLLLLLL..LLLLLLLL.LLLLLL.LLL.L.LLLLLLLL
+LLLLLLLLLLLLLLLLLLLLLLLLLLL.LLLLL.LLLLL.LLLL.LL.L.LLLLLLLLL.LLLLLLLLLLLLLLLLLLLLLL.LLLLLLLL
+LLLLLLLLLL.LLLLL.LL.LLLLLLLLLLLLL.LLLLL.LLLL.LLLLLLLLLLLLLLLLLLLLLLLL.LLLLLLLLLLLLLLLLLLLLL
+...LLL.LL.LL.LLL......L.L.L..L..L....L........L........L...LL....L.LLL....LLL..L.......LLLL
+LLLLLLLLLL.LLLLLLLL.LLLLLLL.LLLLL.LLLLL.LLLLLL.LL.LLLLLLLLL.L.LLL.LLL.LLL.LLLLLLLLLLLLLLLLL
+LLLLLLLLLLLLLLLLLLLL.LLLLLLLLLLLL.LLLLL.LLLL.LLLL.LLL.LLLLL.LLLLLLLLL.LLLLLL.LLLLL.LLLLLLLL
+LLLLLLLLLLLLLLLLLLL.LLLLLLL.LLLLL.LLLLL.LLLLLLL.L.LLLLLLLL..LLLLLLLLL.LLLLLL.LLLLL.LLLLLLLL
+LLLLLLLLLL.LLLLLLLLL.LLLLLL.LLLLL.LLLLL.LLLL.LLLLLLLLLLLLLL.LLLLLLLLL.LLLLLL.LLLLL.LLLLLL.L
+LLLLLLLLLL.LLLLLLLL.LLLLLLL.LLLLL.LLLLLLLLLL.LLLL.LLLLLLLLL..LLLLLLL..LLLLLL.LLLLL.LLLLLL.L
+LLLLLLLLLL.LLLLLLLLLL.LLLLL.LLLLL.LLLLL.LLLL.LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL.LLLLLLLLLLLLL.
+LLLLLLLLLL.LL.LLLLL.LLLLLLLLLLLLLLLLLLL.LLLL.LLLLLLL.LLLLLL.LLL.LLLLL.LLLLLLLLLLLLLLLLLLLLL
+LL.LL.LLLLLLLLLLLLLLLLLLLLLLLLLLL.LLLLL.LLLL.LLLL.LLLLLLLLLLLLLLLL.L..LL.LLL.LLLLLLLLLLLLLL
+L.L........L...LL.L..L....LLLL...LL.L......L.L....L...L.L..LL......LL......L....L..L.LL..L.
+LLLLLLLLLLLLLLLLLLL..L.LLLL.L.LLLLLLLLL.LLLLLLLLL.LLLLLLLLL..LLLLLL.L.L..LLL.LLLLL.LLLLLLLL
+LLLLLLLL.L.LLLL.LLL.LLLLLLLLLLLLL.LLLLL.LLLLLLLLL.LLLLLLLLL.LLLLLLLLL.LLLLLLLLLLLLLLLLLLLLL
+LLLLLLLLLL.LLLLLLLLLLLLLLLL.LLLLL.LLLLL.LLLLLL.LL.L.LLLLLLLLLLLLLLLLLLLLLLLL.LLLLL.LLLLLL.L
+LLLLLLLLL..LLLLLLLLLLLLLLLL.LLLLL.LLLLLLLLLLLLLLL.LLLLLLLLLLLLLLLLLLL.L.LLLL.LLLLLLLLLLLLLL
+LLLLLLLLLLLLLLLLLLL.LLLLLLLLLLLLL.LLLLL.LLLLLLLLLLLLLLLLLLLLLLLLL.LLL.LLLLLL.LLLLL.LLLLLLLL
+LLLLLLLLLLLLLLLLLLL.LLLL.LL.LLLLL.LLLLL.LLLL.LLLL.LLLLLLLLL.LLLLLLLLLLLLLLLL.LLLLLLLLLLLLLL
+LLLLLLLLLLLLLLLL..L.LLLLLLL.LLLLL.LLL.L.LLLL..LLLLLLLLLLLLL.LLLLLLLLL.LLLLLL.LLLLLLLLLLLLLL
+LLLLLLLLLLLLLLLLLLL.LLLLLLL.LLLLLLLLLLL.LLLL.LLLLLLLLLLLLLL.LLLLLLLLL.LLLLLLLLLLLL.LLLLLLLL
+...LL......L..LL.....L.LLLLLL..LL.LLL...L.L...LLL.LL........L......LLL..L.L.L.L..L..LLL.L..
+LL.LLL.LLL.LLLLLLLL.L.LLLLL.LLLLL.L.LLL.LLLL.LLLL.LLLLLLLLL.LLLLLLLLL.LLLLLLLLLLLLLLLLLLLLL
+LLLLLLLLLLLLLLLLLLL.LLLLLLL.LLLLLLLLLLLLLLLL.LLLL.LLLLLLLLL.LLLLLLLL.LLLLLLL.LLLLL.LLLLLLLL
+LLLLLLLLLL.LLLLLLLL.LLLLLLL.LLLLL.LLLLL.L.LL.LLLL..LLLLL.LL.LLLLLLLLL.LLLLLL.LLLLL.LLLLLLLL
+LLL.LLLLL..LLLLLLLL.LLLLL.L.LLLLL.LLLLL.LLL.LLLLL.LLLLLLLLL.LLLLLLLLL.LLLLLLLLLLLL.LL.LLLL.
+LLLLLLLLLLLLLLLLLLL.LLL.LLL.LLLL.LLLLLL.LL.L.LLLLLLLLLLLLLL.LLLLLLLLL.LLLLLL.LLLLL.LLLLLLLL
+.......LLL....LLL.LL.L.L.L....LLL..L..L...L.LL.LLLL...LL............LL..LL....L..L...L.LLLL
+LLLLLLLLLL.LLLLLLLL.LLLLLLL.LLLLL.LLLLL.LLLLLLLLLLLLLLLLLLL.LLLLLLLLLLLLLLLL.LLLLL.LLLL.LLL
+LLLLLLLLLLLLLLLLLLLLLLLLLLL.LLLLL.LLLLL.LLLLLLLLL.LLLLLLLLLLLLL.LLLLL.LLLL.LLLLLL..L.LLLLLL
+LLLLLLLLLL.LLLLLLLL.LLLLLLL.LLLLL.LLLLLLLLLL.LLLL.LLLLLLLLL.LLLLLLLLL.LLLLLL.LLLLL.LLLLLLLL
+LLLLL.LLLL.LLLLLLLL.LLLLLLL..LLLL.LLLLLLLLLL.LLLL.LLLLLLLLL.LLL.LLLLL.LLLLLL.LLLLL.LLLLLLLL
+LLLLLLLLLLLLLLLLLLL.LLLLLLLLLLLLL.LLLLLLLLLLLLLLLLLLLL.LLLL.LLLLLLLLL.LLLLLLLLLLL..LLLL.LLL
+LLLLLLLLLL.LLLLLLL..LLLLLLL.LLLLL..LLLL.LLLL.LLLL.LLLLLLLLL.LLLLLLLLL.LLLLLL.LLLLL.LLLLLLLL
+LLLLLLLLL.LLLLLLLLL.LLLLLLL.LLLL..LLLLL.LLLL.LLLL.LLLLLLLLL.L.LLLLLLL.LLLLLLLLLLLL.L.LLLLLL
+LLLLLLLLLL.LLLLL.L..LLLLLLL.LLLLL.LLLLL.LLLL.LLLLLLLLLLLLLL.LLLLLLLLL.LLLLLL.LLLLL.LLLLLLLL
+.....L...L..L.L..L.LLLLLLLLL....L.LL...LL...L.LL..L..L.L..L.L.....L...L.LL...L.L.......L..L
+LLLLLLLLLLLLLLLLLLL.LLLLL.L.LLLLL.LLLLL.LLLL.LLLLLLLLLLLLLL.LLLLLLLLL.LLLLLL.LLLLL.LLLLLLLL
+LLLLLLLLLLLLLLLLLLLLLLLLLLL.LLLLL.LLLLLLLLLLLLLLL.LLLLLLLLL.LLLLLLLLLLLLLLLL.LLLLL.LLLLLLLL
+LLLLLLLLLLLLLLLLLLL.LLLLLLL.LLLLL.LLLLL.LLLL.LL.LLLLLLLLLLL.LLLLLLLLL.LLLLLL.LLLLL.LLLLLLLL
+LLLLLLLLLL.LLLLLLLLLLLL.LLL.LLLLL.LLL.L.LLLL.LLLLLLLLLLLLLL.LLLLLLLLLLLLLLLL.LLLLL.LLLLLLLL
+LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL.LLLLL.LLLL.LLLL.LLLLLLLLL.LLLLLLLLL.LLLLLLLLLLLL.LLLLLLLL
+LLLLLLLL.L.LLLLLLLL.LLLLLLL.L.LLL.LLLLL.LLLLLLLLLLLLLLLLLLL.LLLLLLLLL.LLLLLL.LLLLL.LLLLLLLL
+LLLLLLLLLL.LLL.LLLL.LLLLLLL.LL.LL.LLLLL.LLLL.LLLL.LLLLLLLLLLLLLLLLLLL.LLLLLL.LLLLLLLLLLLLL.
+LLLLLLLLLL.LLLLLLL..LLLLLLL.LLLLL.LLLLL.LLLLLLLLL.LLL.LLLLL.LLLLLLLLL.LLLLLLLLLLLLLLLLLLLLL
+LLLLLLLLLL.LLLLLLLL.LLLLLLLLLLLLL.LLLLL.LLL..LLLL.LLLLLLL.L.LLLLLLLLL..LLLLLLLLLLLLLLLLLLL.

day11/main.go

@@ -0,0 +1,299 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"strings"
+)
+
+func main() {
+	input, err := ioutil.ReadFile("input.txt")
+	if err != nil {
+		panic(err.Error())
+	}
+
+	wr := NewWaitingRoom(string(input))
+
+	// Part One
+	complete, _ := SimulateSeating(wr)
+	fmt.Printf("Answer 1: %v occupied seats\n", complete.OccupiedSeatCount())
+
+	// Part Two
+	complete, _ = SimulateAlternateSeating(wr)
+	fmt.Printf("Answer 2: %v occupied seats, using alternate strategy\n", complete.OccupiedSeatCount())
+}
+
+// WaitingRoom represents a collection of seats in a waiting room
+type WaitingRoom struct {
+	seats [][]rune
+}
+
+// NewWaitingRoom creates a WaitingRoom from a string input
+func NewWaitingRoom(input string) WaitingRoom {
+	var wr = WaitingRoom{}
+	for _, row := range strings.Split(input, "\n") {
+		if len(row) == 0 {
+			continue
+		}
+
+		var seats []rune
+		for _, seat := range row {
+			seats = append(seats, seat)
+		}
+		wr.seats = append(wr.seats, seats)
+	}
+
+	return wr
+}
+
+// Print a WaitingRoom to the console
+func (wr WaitingRoom) Print() {
+	for _, row := range wr.seats {
+		for _, seat := range row {
+			fmt.Printf("%c", seat)
+		}
+		fmt.Printf("\n")
+	}
+}
+
+// OccupiedSeatCount returns the number of occupied seats in the waiting room.
+func (wr WaitingRoom) OccupiedSeatCount() int {
+	count := 0
+
+	for _, row := range wr.seats {
+		for _, seat := range row {
+			if seat == '#' {
+				count++
+			}
+		}
+	}
+
+	return count
+}
+
+// Clone creates an exact duplicate of a WaitingRoom
+func (wr WaitingRoom) Clone() WaitingRoom {
+	var cp = WaitingRoom{}
+
+	for _, row := range wr.seats {
+		var newRow []rune
+
+		for _, seat := range row {
+			newRow = append(newRow, seat)
+		}
+
+		cp.seats = append(cp.seats, newRow)
+	}
+
+	return cp
+}
+
+// AdjacentSeatCount returns the number of occupied seats
+// in the eight seat positions next to a given x,y
+// coordinate in the WaitingRoom:
+// Left, Right, Up, Down, and Diagonal.
+func (wr WaitingRoom) AdjacentSeatCount(x, y int) int {
+	count := 0
+
+	for i := x - 1; i <= x+1; i++ {
+		for j := y - 1; j <= y+1; j++ {
+			// Ignore the target seat
+			if i == x && j == y {
+				continue
+			}
+
+			// Check WaitingRoom bounds
+			if i < 0 || i >= len(wr.seats) {
+				continue
+			}
+			if j < 0 || j >= len(wr.seats[i]) {
+				continue
+			}
+
+			if wr.seats[i][j] == '#' {
+				count++
+			}
+		}
+	}
+
+	return count
+}
+
+// AlternateAdjacentSeatCount returns the number of occupied
+// seats, considering the first chair that is visible in
+// each of the eight directions around the target seat.
+func (wr WaitingRoom) AlternateAdjacentSeatCount(x, y int) int {
+	count := 0
+
+	for _, dir := range []string{"N", "NW", "W", "SW", "S", "SE", "E", "NE"} {
+		seat, err := wr.FindDirectionalSeat(dir, x, y)
+		if err != nil {
+			continue
+		}
+		if seat == '#' {
+			count++
+		}
+	}
+
+	return count
+}
+
+var translations = map[string][]int{
+	"N":  {0, -1},
+	"NW": {1, -1},
+	"W":  {1, 0},
+	"SW": {1, 1},
+	"S":  {0, 1},
+	"SE": {-1, 1},
+	"E":  {-1, 0},
+	"NE": {-1, -1},
+}
+
+func translate(dir string, x, y int) (int, int) {
+	offset, exists := translations[dir]
+	if !exists {
+		panic("Invalid direction lookup")
+	}
+
+	return x + offset[0], y + offset[1]
+}
+
+// FindDirectionalSeat returns the first seat found in a given direction
+// from a given set of coordinates.
+func (wr WaitingRoom) FindDirectionalSeat(direction string, x, y int) (rune, error) {
+
+	var seat rune
+
+	for {
+		xPrime, yPrime := translate(direction, x, y)
+
+		// Check X bounds
+		if xPrime < 0 || xPrime >= len(wr.seats[0]) {
+			return seat, errors.New("out of bounds")
+		}
+
+		// Check Y bounds
+		if yPrime < 0 || yPrime >= len(wr.seats) {
+			return seat, errors.New("out of bounds")
+		}
+
+		// If this new spot contains a seat we
+		// will return it. If not, carry on.
+		if wr.seats[yPrime][xPrime] == 'L' || wr.seats[yPrime][xPrime] == '#' {
+			return wr.seats[yPrime][xPrime], nil
+		}
+
+		x = xPrime
+		y = yPrime
+	}
+}
+
+// IsEqual tells us if two WaitingRooms have an identical configuration
+func IsEqual(wrA, wrB WaitingRoom) bool {
+	for i := 0; i < len(wrA.seats); i++ {
+		for j := 0; j < len(wrA.seats[i]); j++ {
+			if wrA.seats[i][j] != wrB.seats[i][j] {
+				return false
+			}
+		}
+	}
+
+	return true
+}
+
+// DoTick simulates a single round of seating in the wating room.
+func DoTick(wrA WaitingRoom) WaitingRoom {
+	var wrB = wrA.Clone()
+
+	for i := 0; i < len(wrA.seats); i++ {
+		for j := 0; j < len(wrA.seats[i]); j++ {
+
+			// Start by copying the current seat value to the new waiting room
+			wrB.seats[i][j] = wrA.seats[i][j]
+
+			// Rule:
+			// If a seat is empty (L) and there are no occupied seats adjacent to it,
+			// the seat becomes occupied.
+			if wrA.seats[i][j] == 'L' && wrA.AdjacentSeatCount(i, j) == 0 {
+				wrB.seats[i][j] = '#'
+			}
+
+			// Rule:
+			// If a seat is occupied (#) and four or more seats adjacent to it are
+			// also occupied, the seat becomes empty.
+			if wrA.seats[i][j] == '#' && wrA.AdjacentSeatCount(i, j) >= 4 {
+				wrB.seats[i][j] = 'L'
+			}
+		}
+	}
+
+	return wrB
+}
+
+// DoAlternateTick simulates a single round of seating in the wating room,
+// using alternate rules.
+func DoAlternateTick(wrA WaitingRoom) WaitingRoom {
+	var wrB = wrA.Clone()
+
+	for i := 0; i < len(wrA.seats); i++ {
+		for j := 0; j < len(wrA.seats[i]); j++ {
+
+			// Start by copying the current seat value to the new waiting room
+			// wrB.seats[i][j] = wrA.seats[i][j]
+
+			// Rule:
+			// If a seat is empty (L) and there are no occupied seats adjacent to it,
+			// the seat becomes occupied.
+			if wrA.seats[i][j] == 'L' && wrA.AlternateAdjacentSeatCount(j, i) == 0 {
+				wrB.seats[i][j] = '#'
+			}
+
+			// Rule:
+			// If a seat is occupied (#) and five or more seats adjacent to it are
+			// also occupied, the seat becomes empty.
+			if wrA.seats[i][j] == '#' && wrA.AlternateAdjacentSeatCount(j, i) >= 5 {
+				wrB.seats[i][j] = 'L'
+			}
+		}
+	}
+
+	return wrB
+}
+
+// SimulateSeating runs a waiting room through a full seating process
+func SimulateSeating(wr WaitingRoom) (WaitingRoom, int) {
+	rounds := 0
+	var previous WaitingRoom = wr
+
+	for {
+
+		next := DoTick(previous)
+
+		if IsEqual(next, previous) {
+			return previous, rounds
+		}
+
+		previous = next
+		rounds++
+	}
+}
+
+// SimulateAlternateSeating runs a waiting room through a full seating process
+func SimulateAlternateSeating(wr WaitingRoom) (WaitingRoom, int) {
+	rounds := 0
+	var previous WaitingRoom = wr
+
+	for {
+
+		next := DoAlternateTick(previous)
+
+		if IsEqual(next, previous) {
+			return previous, rounds
+		}
+
+		previous = next
+		rounds++
+	}
+
+}