2022 Day 9 Python

2022/day09.py

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+import numpy as np
+with open('input/09', 'r') as file:
+	lines = file.read().strip().split('\n')
+dtype = np.int32
+
+directions_array = np.array([[1,0], [-1,0], [0,1], [0,-1]], dtype=dtype)
+directions_dict = {'R': directions_array[0], 'L': directions_array[1], 'D': directions_array[2], 'U': directions_array[3]}  # Positive down for visualization
+
+def move_tail(rope: np.array):
+	for i in range(1, rope.shape[0]):
+		dx, dy = rope[i-1,:] - rope[i,:]
+		if abs(dx) > 1 and dy == 0:
+			rope[i,0] += 1 if dx > 0 else -1
+		elif abs(dy) > 1 and dx == 0:
+			rope[i,1] += 1 if dy > 0 else -1
+		elif abs(dx) + abs(dy) > 2:
+			rope[i,0] += 1 if dx > 0 else -1
+			rope[i,1] += 1 if dy > 0 else -1
+
+def simulate_rope_drag(length: int, lines: list[str]):
+	rope = np.zeros([length,2], dtype=dtype)
+	visited = {(rope[-1,0], rope[-1,1])}
+	for line in lines:
+		dir_vector = directions_dict[line[0]]
+		amount = int(line[2:])
+		for i in range(amount):
+			rope[0,:] += dir_vector
+			move_tail(rope)
+			visited.add((rope[-1,0], rope[-1,1]))
+	return visited
+
+def visualise_cells(visited: set, size=20):
+	vis_lol = [['#' if (x,y) in visited else '.' for x in range(-size, size)] for y in range(-size, size)]
+	vis_str = '\n'.join(''.join(line) for line in vis_lol)
+	print(vis_str)
+
+
+visited_part_1 = simulate_rope_drag(2, lines)
+print(f'Part 1: String length of 2 - tail visits {len(visited_part_1)} cells')
+visited_part_2 = simulate_rope_drag(10, lines)
+print(f'Part 2: String length of 10 - tail visits {len(visited_part_2)} cells')
+
+if input('Visualise part 1 cells? [y/N]: ').lower() == 'y':
+	visualise_cells(visited_part_1, 70)
+	print()
+if input('Visualise part 2 cells? [y/N]: ').lower() == 'y':
+	visualise_cells(visited_part_2, 70)