Day 19

day19/part1.py

@@ -0,0 +1,39 @@
+#!/usr/bin/env python3
+import re
+
+lines = (x.strip() for x in open("input.txt"))
+rules = {}
+
+
+def yield_rule(line, rule):
+    if len(rule) > 0:
+        elem, *tail = rule
+        for rest in check(line, elem):
+            yield from yield_rule(rest, tail)
+    else:
+        yield line
+
+
+def check(line, idx):
+    rs = rules[idx]
+    if isinstance(rs, str):
+        if line.startswith(rs):
+            yield line[len(rs):]
+    else:
+        for rule in rules[idx]:
+            yield from yield_rule(line, rule)
+
+
+sum = 0
+for line in lines:
+    if ":" in line:
+        idx, r = line.split(": ")
+        idx = int(idx)
+        r = r[1:len(r)-1] if r.startswith('"') else [[int(num) for num in x.split()] for x in r.split(" | ")]
+        rules[idx] = r
+    elif line != "":
+        for rest in check(line, 0):
+            if rest == "":
+                sum += 1
+print(sum)
+exit(0)