2025 day 6

adventofcode/2025/day6/day6.py

@@ -0,0 +1,58 @@
+#!/usr/bin/env python3
+import fileinput
+import re
+from functools import reduce
+from operator import mul
+
+
+def calc(stack, operator):
+    if operator == "+":
+        return sum(int(x) for x in stack)
+    elif operator == "*":
+        return reduce(mul, map(int, stack))
+    else:
+        raise NotImplementedError(operator)
+
+
+def part1(inp):
+    lines = [re.split(r"\s+", x.strip()) for x in inp]
+    total = 0
+    for col in zip(*lines):
+        operands, operator = col[:-1], col[-1]
+        result = calc([int(x) for x in operands], operator)
+        total += result
+    print("Part 1: ", total)
+
+
+def part2(lines):
+    total = 0
+    max_len = max(len(x) for x in lines)
+    numbers = []
+    operator = None
+    for i in range(max_len - 1, -1, -1):
+        digits = []
+        for line in lines:
+            if i >= len(line):
+                continue
+            ch = line[i]
+            if ch in "*+":
+                operator = ch
+                break
+            elif ch != " ":
+                digits.append(ch)
+
+        if digits:
+            numbers.append(int("".join(digits)))
+
+        if operator is not None:
+            total += calc(numbers, operator)
+            numbers = []
+            operator = None
+
+    print("Part 2: ", total)
+
+
+if __name__ == "__main__":
+    lines = [x.rstrip() for x in fileinput.input()]
+    part1(lines)
+    part2(lines)