chore: create new project structure and aoc.py runner script

adventofcode/2020/day14/day14.py

@@ -0,0 +1,58 @@
+#!/usr/bin/env python3
+from collections import defaultdict
+
+
+def part1(infile):
+    memory = defaultdict(int)
+    for line in infile:
+        left, right = line.split("=")
+        if left.startswith("mask"):
+            one_mask = right.translate(right.maketrans("X", "0"))
+            zero_mask = right.translate(right.maketrans("X10", "001"))
+        else:
+            address = int(left.split("[")[1].rstrip("] "))  # mem[42] -> 42
+            value = int(right.rstrip())
+            memory[address] = value & ~int(zero_mask, 2) | int(one_mask, 2)
+
+    return sum(memory.values())
+
+
+def part2(infile):
+    memory = defaultdict(int)
+    for line in infile:
+        left, right = line.split(" = ")
+        if left.startswith("mask"):
+            mask = right.rstrip()
+        else:
+            value = right.rstrip()
+            address = apply_mask(left.split("[")[1].rstrip("] "), mask)
+            for addr in generate_floating_addresses(address):
+                memory[int(addr, 2)] = int(value)
+    return sum(memory.values())
+
+
+def apply_mask(address, mask):
+    address = bin(int(address)).lstrip("0b")
+    address = address.zfill(36)
+    for index, bit in enumerate(mask):
+        if bit == "1":
+            address = address[:index] + "1" + address[index + 1 :]
+        elif bit == "X":
+            address = address[:index] + "X" + address[index + 1 :]
+    return address
+
+
+def generate_floating_addresses(address):
+    index = address.find("X")
+    if index == -1:
+        return [address]
+    a1 = generate_floating_addresses(address[:index] + "0" + address[index + 1 :])
+    a2 = generate_floating_addresses(address[:index] + "1" + address[index + 1 :])
+    return a1 + a2
+
+
+if __name__ == "__main__":
+    import fileinput
+    lines = [x for x in fileinput.input()]
+    print(part1(lines))
+    print(part2(lines))