2020 day 16

2020/d16.py

@@ -0,0 +1,88 @@
+from lib import get_data, str_to_ints
+
+data = get_data(__file__)
+
+dps = []
+ranges = []
+lines = (l for l in data.splitlines())
+
+index = 0
+for line in lines:
+    if line.strip() == "":
+        break
+    if line.startswith("departure"):
+        dps.append(index)
+    a, b, c, d = str_to_ints(line.replace("-", " "))
+    # ranges.append(((a, b), (c, d)))
+    ranges.append((a, b, c, d))
+    index += 1
+
+next(lines)
+my_ticket = str_to_ints(next(lines))
+next(lines)
+next(lines)
+
+error = 0
+valid = []
+fields = []
+for line in lines:
+    # print(line)
+    has_error = False
+    field = []
+    for x in str_to_ints(line):
+        no_match = True
+        field.append(set())
+        for i, (a, b, c, d) in enumerate(ranges):
+            if a <= x <= b:
+                field[-1].add(i)
+                no_match = False
+            elif c <= x <= d:
+                field[-1].add(i)
+                no_match = False
+        if no_match:
+            has_error = True
+            error += x
+    if not has_error:
+        valid.append(line)
+        fields.append(field)
+
+base = fields[0]
+for field in fields[1:]:
+    for i in range(len(field)):
+        base[i] &= field[i]
+print(error)
+
+used = set()
+done = False
+base = [list(xs) for xs in base]
+while not done:
+    done = True
+    single = None
+    for xs in base:
+        if len(xs) == 1 and xs[0] not in used:
+            single = xs[0]
+            used.add(single)
+            break
+
+    if single is not None:
+        for xs in base:
+            if len(xs) == 1:
+                continue
+            if single in xs:
+                xs.remove(single)
+
+    for xs in base:
+        if len(xs) != 1:
+            done = False
+            break
+
+mapping = []
+for xs in base:
+    (x,) = xs
+    mapping.append(x)
+
+r = 1
+for i, v in zip(mapping, my_ticket):
+    if i in dps:
+        r *= v
+print(r)

README.md

@@ -154,8 +154,8 @@ Solutions and utility script for Advent of Code challenges in Python.
 - Day 13: 18:00 (I don't really understand the CRT to be honest)
 - Day 14: 40:26 (Made a bunch of mistakes even misunderstanding Python)
 - Day 15: 17:57 (Too slow for an easy one like this)
-- Day 16:
+- Day 16: 33:00 (Not too unhappy really.)
-
+- Day 17:
 
 ## AoC 2022