day9-part2-take1.py

# open the input file and read the lines
with open("input.txt") as f:
    lines = f.readlines()

# initialize the head and tail at the same position
head = (0, 0)
tail = (0, 0)

# initialize the 10 parts of the rope
parts = [(0, 0) for _ in range(10)]

# parse the list of movements for the head from the input file
movements = [line.strip() for line in lines]

# create a set to store the positions visited by the tail (part 10)
tail_positions = set()

# iterate over the movements and update the position of the head and tail
for move in movements:
    direction, steps = move.split()
    steps = int(steps)
    
    for i in range(steps):
        # update the position of the head
        if direction == "R":
            head = (head[0] + 1, head[1])
        elif direction == "L":
            head = (head[0] - 1, head[1])
        elif direction == "U":
            head = (head[0], head[1] + 1)
        elif direction == "D":
            head = (head[0], head[1] - 1)
        
        # update the position of the 10 parts of the rope
        for i in range(9, 0, -1):
            parts[i] = parts[i-1]
        parts[0] = head
        
        # add the position of the tail (part 10) to the set of tail positions
        tail_positions.add(parts[-1])
        
print("Number of unique positions visited by the tail:", len(tail_positions))