Day 14

day14/part2.py

@@ -0,0 +1,34 @@
+import re
+
+lines = (x.strip() for x in open("input.txt"))
+mem = {}
+regex_mask = re.compile(r"mask = (.+)")
+regex_mem = re.compile(r"mem\[(.*)] = (.+)")
+mask = ""
+
+
+def combination(res, sum=0):
+    if len(res) == 0:
+        yield sum
+    else:
+        head, tail = res[0], res[1:]
+        if head != 'X':
+            yield from combination(tail, sum=sum*2+int(head))
+        else:
+            yield from combination(tail, sum=sum*2)
+            yield from combination(tail, sum=sum*2+1)
+
+
+for line in lines:
+    match = regex_mask.match(line)
+    if match is not None:
+        mask = match.group(1)
+    else:
+        match = regex_mem.match(line)
+        addr, dec = list(map(int, match.groups()))
+        bin = format(addr, '036b')
+        res = "".join((a if b == '0' else b) for a, b in zip(bin, mask))
+        for x in combination(res):
+            mem[x] = dec
+
+print(sum(map(lambda x: mem[x], mem)))