diff --git a/2022/day23.py b/2022/day23.py
new file mode 100644
index 0000000..b35257f
--- /dev/null
+++ b/2022/day23.py
@@ -0,0 +1,86 @@
+from helpers import *
+lines = read_day(23).split('\n')
+sample_lines = '''
+....#..
+..###.#
+#...#.#
+.#...##
+#.###..
+##.#.##
+.#..#..
+'''.strip().split('\n')
+
+def get_intention(round, elves, x, y):
+	adj_nw = (x-1,y-1) in elves
+	adj_w = (x-1,y) in elves
+	adj_sw = (x-1,y+1) in elves
+	adj_n = (x,y-1) in elves
+	adj_s = (x,y+1) in elves
+	adj_ne = (x+1,y-1) in elves
+	adj_e = (x+1,y) in elves
+	adj_se = (x+1,y+1) in elves
+	if adj_nw or adj_n or adj_ne or adj_w or adj_e or adj_sw or adj_s or adj_se:
+		for i in range(4):
+			direction = (round + i) % 4
+			if (direction == 0) and not (adj_n or adj_nw or adj_ne):
+				return (x,y-1)  # move north
+			if (direction == 1) and not (adj_s or adj_sw or adj_se):
+				return (x,y+1)  # move south
+			if (direction == 2) and not (adj_w or adj_nw or adj_sw):
+				return (x-1,y)  # move west
+			if (direction == 3) and not (adj_e or adj_ne or adj_se):
+				return (x+1,y)  # move east
+	return (x,y)  # no movement
+
+def simulate(lines: list[str], rounds: int = 10) -> set[tuple[int,int]]:
+	# position = np.array([[c=='#' for c in line] for line in lines], dtype=np.bool8)
+	elves = set()
+	for row, line in enumerate(lines):
+		for col, c in enumerate(line):
+			if c == '#':
+				elves.add((col, row))
+
+	for round in range(rounds):
+		if round == 10:
+			print(f'*** Part 1: ground tiles after round #10: {get_rect(elves)} ***')
+		# else:
+		# 	print(f'\tground tiles before round #{round+1}: {get_rect(elves)}')
+		# print(f'performing round #{round+1}')
+		next_elves = {}
+		for x,y in sorted(elves, key=lambda p: (p[1], p[0])):
+			intention = get_intention(round, elves, x, y)
+			# print(f'{x,y} wants to move to {intention}')
+			next_elves[intention] = next_elves.get(intention, []) + [(x,y)]
+		old_elves = elves
+		elves = set()
+		for position, elf_intentions in next_elves.items():
+			if len(elf_intentions) == 1:
+				elves.add(position)
+			else:
+				# print(f'conflict: {len(elf_intentions)} elves tried to move to {position}')
+				elves |= set(elf_intentions)  # neither move
+		if old_elves == elves:
+			print(f'*** Part 2: No elves moved in round #{round+1} ***')
+			break
+	print(f'Final ground tiles: {get_rect(elves)}')
+	return elves
+
+def get_rect(elves: set[tuple[int,int]]):
+	x0, x1, y0, y1 = None, None, None, None
+	for x,y in elves:
+		if x0 is None or x < x0:
+			x0 = x
+		if x1 is None or x > x1:
+			x1 = x
+		if y0 is None or y < y0:
+			y0 = y
+		if y1 is None or y > y1:
+			y1 = y
+	# print(f'Elves in rectangle from x:{x0}~{x1}, y:{y0}~{y1}')
+	# for y in range(y0, y1+1):
+	# 	print(''.join(('#' if (x,y) in elves else '.' for x in range(x0,x1+1))))
+	rect_size = (x1-x0+1)*(y1-y0+1)  # inclusive
+	return rect_size - len(elves)
+
+simulate(sample_lines, 100)
+simulate(lines, 100000)
diff --git a/2022/input/23 b/2022/input/23
new file mode 100644
index 0000000..5307fc8
--- /dev/null
+++ b/2022/input/23
@@ -0,0 +1,73 @@
+.##.#.....##.#.......#..#####....#####...#..###..#.#..#...#.##...###.##.#
+....##..##..........##.#..#.##...#.#.#...##..#..#####.#..#..#.#..#..####.
+#.####.##..##.##.#####.#####...#.....#...####..##.##..###..##..#####..#..
+..###.#.##....#.###.#..#####..##.####..###.####.######....###.#####...#..
+#.#..#..#....#...####.#.....##..#.###.....##.#.#...#.#.##.######.#.#...##
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