day12.py

with open('data.txt') as file:
    data = file.read().splitlines()

# part 1

DIRECTIONS = {
    0: 'N',
    90: 'E',
    180: 'S',
    270: 'W',
}

class Ship:
    def __init__(self):
        self.bearing = 90
        self.position = {"E": 0, "N": 0}
    
    def move(self, direction, units):
        print(f"Moving {direction} {units}")
        if direction in ["L", "R"]:
            new_bearing = (self.bearing + units) % 360 if direction == "R" else (self.bearing - units) % 360
            self.bearing = new_bearing
            print(self)
        
        elif direction in ["E", "W", "N", "S"]:
            if direction == "E":
                self.position['E'] += units
            elif direction == "W":
                self.position['E'] -= units
            elif direction == "N":
                self.position['N'] += units
            elif direction == "S":
                self.position['N'] -= units
            print(self)
        # forward
        else:
            self.move(DIRECTIONS[self.bearing], units)
        
    def manhattan(self):
        return abs(self.position['E']) + abs(self.position['N'])
        
    def __str__(self):
        return f"bearing: {self.bearing}\nposition: {self.position}"

dirs = ['F10', 'N3', 'F7', 'R90', 'F11']
ship = Ship()
for d in dirs:
    ship.move(d[0], int(d[1:]))
assert ship.manhattan() == 25


# part 2

class Ship:
    def __init__(self):
        self.bearing = 0
        self.position = {"E": 0, "N": 0}
        self.waypoint = {"E": 10, "N": 1}
    
    def move(self, direction, units):
        if direction in ["L", "R"]:
            new_bearing = (self.bearing + units) % 360 if direction == "R" else (self.bearing - units) % 360
            while self.bearing != new_bearing:
                self.waypoint = {'E': self.waypoint['N'] * -1, 'N': self.waypoint['E']}
                self.bearing -= 90
                if self.bearing >= 360:
                    self.bearing = 0
                if self.bearing < 0:
                    self.bearing = 270
        
        elif direction in ["E", "W", "N", "S"]:
            if direction == "E":
                self.waypoint['E'] += units
            elif direction == "W":
                self.waypoint['E'] -= units
            elif direction == "N":
                self.waypoint['N'] += units
            elif direction == "S":
                self.waypoint['N'] -= units
        
        # forward
        else:
            self.position['E'] += self.waypoint['E'] * units
            self.position['N'] += self.waypoint['N'] * units
    
    def manhattan(self):
        return abs(self.position['E']) + abs(self.position['N'])
    
    def __str__(self):
        return f"bearing: {self.bearing}\nposition: {self.position}\nwaypoint: {self.waypoint}"

dirs = ['F10', 'N3', 'F7', 'R90', 'F11']
ship = Ship()
for d in dirs:
    ship.move(d[0], int(d[1:]))
assert ship.manhattan() == 286