day9_take2.py

# Parse the input
with open('sample.txt') as f:
    moves = [line.strip() for line in f]

# Initialize the head and tail positions
head_pos = [0, 0]
tail_pos = [0, 0]

# Keep track of the positions the tail has visited
visited = set()
visited.add((0, 0))

# Define a function to move the head and update the tail position
def movef(direction, steps):
    global head_pos, tail_pos, visited
    print(f"move:{direction} s:{steps}")
    # Update the head position
    if direction == 'U':
        head_pos[1] += steps
    elif direction == 'D':
        head_pos[1] -= steps
    elif direction == 'L':
        head_pos[0] -= steps
    elif direction == 'R':
        head_pos[0] += steps

    # Update the tail position
    if head_pos[0] == tail_pos[0]:
        # Tail moves vertically
        if head_pos[1] > tail_pos[1]:
            tail_pos[1] += 1
        else:
            tail_pos[1] -= 1
    elif head_pos[1] == tail_pos[1]:
        # Tail moves horizontally
        if head_pos[0] > tail_pos[0]:
            tail_pos[0] += 1
        else:
            tail_pos[0] -= 1
    else:
        # Tail moves diagonally
        if head_pos[0] > tail_pos[0]:
            tail_pos[0] += 1
        else:
            tail_pos[0] -= 1
        if head_pos[1] > tail_pos[1]:
            tail_pos[1] += 1
        else:
            tail_pos[1] -= 1

    # Add the new tail position to the set of visited positions
    visited.add((tail_pos[0], tail_pos[1]))
    print(f"{head_pos},{tail_pos}")

# Loop through the moves and apply them
for move in moves:
    direction = move[0]
    steps = int(move[1:])
    movef(direction, steps)

# Print the number of unique positions the tail visited
print(len(visited))