Completed day 18 of year 2024

Author: fschatbot

2024/18.py

@@ -0,0 +1,93 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+from heapq import heappop, heappush
+
+def parse(data):
+	points = []
+	for point in data.split('\n'):
+		x, y = point.split(',')
+		points.append((int(x), int(y)))
+	
+	return points
+
+split_data = parse
+completed = True
+raw_data = None # Not To be touched
+
+def part1(data):
+	movements = [(0, -1), (0, 1), (1, 0), (-1, 0)]
+	mapSize = 71
+	goal = (70,70)
+	corrupted = data[:1024]
+
+
+	seen = set()
+	queue = [(0,0,0, [(0,0)])]
+	while len(queue) > 0:
+		x, y, steps, path = queue.pop(0)
+
+		for dx, dy in movements:
+			nx, ny = x + dx, y + dy
+			if not (0 <= nx < mapSize and 0 <= ny < mapSize): continue
+			if (nx, ny) in seen: continue
+			if (nx, ny) in corrupted: continue
+			if (nx, ny) == goal:
+				# plot(path+[goal], corrupted, mapSize)
+				return steps+1
+
+			seen.add((nx, ny))
+			queue.append((nx, ny, steps+1, path+[(nx, ny)]))
+	
+	print(seen)
+	print(f"WTF? We saw {len(seen)} locations and still haven't seen the goal!")
+
+def plot(path, walls, size):
+	for y in range(size):
+		for x in range(size):
+			if (x, y) in walls:
+				print('#', end='')
+			elif (x, y) in path:
+				print('O', end='')
+			else:
+				print('.', end='')
+		print()
+
+def hasPath(start, end, blocked, bounds):
+	# Since we don't care much about optimality, this we will implement the A* algorithm
+	movements = [(0, -1), (0, 1), (1, 0), (-1, 0)]
+	(sx, sy), (ex, ey) = start, end
+
+	seen = set()
+	queue = [(abs(ex-sx)+abs(ey-sy), sx, sy, id(0), [sx, sy])] # Heuristic, x, y, unique, path
+	while len(queue) > 0:
+		_, x, y, _, path = heappop(queue)
+
+		for dx, dy in movements:
+			nx, ny = x + dx, y + dy
+			if not (0 <= nx < bounds[0] and 0 <= ny < bounds[1]): continue
+			if (nx, ny) in seen: continue
+			if (nx, ny) in blocked: continue
+			if (nx, ny) == end: return path+[end]
+
+			seen.add((nx, ny))
+			heappush(queue, (abs(ex-nx)+abs(ey-ny), nx, ny, id(0), path+[(nx, ny)]))
+	
+	return False
+
+def part2(data):
+	checking = 1024
+	path = hasPath((0, 0), (70, 70), data[:checking], (71, 71))
+	while True:
+		checking += 1
+		if data[checking-1] in path: # Only update if the current byte disturbs the precalculated path (optimization)
+			path = hasPath((0, 0), (70, 70), data[:checking], (71, 71))
+			if path == False:
+				# plot(hasPath((0, 0), (70, 70), data[:checking-1], (71, 71)), data[:checking], 71)
+				break
+			# plot(path, data[:checking], 71)
+			# print('---')
+		
+		# if checking % 100 == 0: print(f'{checking/len(data):,.2%}')
+	
+	return f'{data[checking-1][0]},{data[checking-1][1]}'