Finish 2019

2019/25_santa.py

@@ -0,0 +1,65 @@
+#!/usr/bin/env python3
+import re
+import sys
+from itertools import combinations
+from intcode import read_program, run
+
+def send_command(droid, command):
+    inputs = map(ord, command + '\n') if command else []
+    buf = [chr(outp) for outp in map(droid.send, inputs) if outp is not None]
+    for outp in droid:
+        if outp is None:
+            break
+        buf.append(chr(outp))
+    return ''.join(buf)
+
+def parse_output(output):
+    assert output.endswith('Command?\n')
+    loc = re.search(r'== (.*) ==', output, re.M).group(1)
+    directions = re.findall(r'- (north|south|east|west)', output)
+    m = re.search(r'Items here:', output)
+    items = re.findall(r'- (.*)', output[m.end(0):]) if m else []
+    return loc, directions, items
+
+def play(droid):
+    opposite_directions = {'north': 'south', 'south': 'north',
+                           'west': 'east', 'east': 'west', '': ''}
+    dangerous_items = {'escape pod', 'giant electromagnet', 'photons',
+                       'molten lava', 'infinite loop'}
+
+    def dfs(prev, direction, path):
+        nonlocal destination_path
+        output = send_command(droid, direction)
+        loc, directions, items = parse_output(output)
+        for item in items:
+            if item not in dangerous_items:
+                send_command(droid, 'take ' + item)
+                inventory.append(item)
+        if loc == 'Pressure-Sensitive Floor':
+            destination_path = tuple(path)
+        if loc not in visited:
+            visited.add(loc)
+            for d in directions:
+                if d != opposite_directions[direction]:
+                    dfs(loc, d, path + [d])
+                    send_command(droid, opposite_directions[d])
+
+    inventory = []
+    destination_path = None
+    visited = {'outside'}
+    dfs('outside', '', [])
+
+    for direction in destination_path[:-1]:
+        send_command(droid, direction)
+
+    for dropnum in range(len(inventory)):
+        for dropitems in combinations(inventory, dropnum):
+            for item in dropitems:
+                send_command(droid, 'drop ' + item)
+            output = send_command(droid, destination_path[-1])
+            if 'Alert!' not in output:
+                return int(re.search(r'\d+', output).group(0))
+            for item in dropitems:
+                send_command(droid, 'take ' + item)
+
+print(play(run(read_program(sys.stdin))))