Day 6!

Author: jcputney

6_1.py

@@ -0,0 +1,46 @@
+moves = ["^", ">", "v", "<"]
+rules = [(-1, 0), (0, 1), (1, 0), (0, -1)]
+
+
+def main():
+    with open("input/6_1.txt") as f:
+        lines = f.read().splitlines()
+
+        obstacles = []
+        current_pos = ()
+        current_dir = ""
+        for line_idx, line in enumerate(lines):
+            for pos_idx, pos in enumerate(line):
+                if pos in moves:
+                    current_dir = moves.index(pos)
+                    current_pos = (line_idx, pos_idx)
+                elif pos == "#":
+                    obstacles.append((line_idx, pos_idx))
+
+        print("Obstacles: ", obstacles)
+        print("Start Position: ", current_pos)
+
+        already_visited = {current_pos}
+        while True:
+            if current_pos[0] == 0 or current_pos[0] == len(lines) - 1 or current_pos[1] == 0 or current_pos[1] == len(lines[0]) - 1:
+                break
+
+            rule = rules[current_dir]
+
+            new_pos = (current_pos[0] + rule[0], current_pos[1] + rule[1])
+            if new_pos in obstacles:
+                current_dir = (current_dir + 1) % 4
+                print("New Direction: ", moves[current_dir])
+                continue
+
+            current_pos = new_pos
+            if current_pos not in already_visited:
+                already_visited.add(current_pos)
+
+            print("New Position: ", current_pos)
+
+        print("Move Count: ", len(already_visited))
+
+
+if __name__ == "__main__":
+    main()

6_2.py

@@ -0,0 +1,69 @@
+import multiprocessing as mp
+
+moves = ["^", ">", "v", "<"]
+rules = [(-1, 0), (0, 1), (1, 0), (0, -1)]
+
+
+def main():
+    lines, obstacles, starting_dir, starting_pos = read_input('input/6_2.txt')
+
+    with mp.Pool(mp.cpu_count()) as pool:
+        results = pool.starmap(check_position, [
+            (lines, obstacles, starting_dir, starting_pos, line_idx, pos_idx)
+            for line_idx, line in enumerate(lines)
+            for pos_idx, pos in enumerate(line)
+            if (line_idx, pos_idx) not in obstacles and (line_idx, pos_idx) != starting_pos
+        ])
+
+    loop_count = sum(results)
+    print("Loop Count:", loop_count)
+
+
+def check_position(lines, obstacles, starting_dir, starting_pos, line_idx, pos_idx):
+    current_pos = starting_pos
+    current_dir = starting_dir
+    already_visited = {(current_pos[0], current_pos[1], current_dir)}
+    new_obstacle = (line_idx, pos_idx)
+
+    while True:
+        if is_at_border(current_pos, lines):
+            return False
+
+        rule = rules[current_dir]
+        new_pos = (current_pos[0] + rule[0], current_pos[1] + rule[1])
+
+        if new_pos in obstacles or new_pos == new_obstacle:
+            current_dir = (current_dir + 1) % 4
+        else:
+            current_pos = new_pos
+
+        current_pos_dir = (current_pos[0], current_pos[1], current_dir)
+        if current_pos_dir in already_visited:
+            return True
+        already_visited.add(current_pos_dir)
+
+
+def is_at_border(pos, lines):
+    return pos[0] == 0 or pos[0] == len(lines) - 1 or pos[1] == 0 or pos[1] == len(lines[0]) - 1
+
+
+def read_input(file_path):
+    with open(file_path) as f:
+        lines = f.read().splitlines()
+
+    obstacles = set()
+    starting_pos = ()
+    starting_dir = -1
+    for line_idx, line in enumerate(lines):
+        for pos_idx, pos in enumerate(line):
+            if pos in moves:
+                starting_dir = moves.index(pos)
+                starting_pos = (line_idx, pos_idx)
+            elif pos == "#":
+                obstacles.add((line_idx, pos_idx))
+
+    return lines, obstacles, starting_dir, starting_pos
+
+
+if __name__ == "__main__":
+    main()