[2024/7] comments

2024/7/script.py

@@ -1,21 +1,28 @@
 from GhostyUtils import aoc
 import operator
 import itertools
+from typing import Iterable, Callable
 
 
-def calibrate(target, operands, operators) -> int:
+def calibrate(target: int, operands: list[int], operators: Iterable[Callable]) -> int:
+    # try all operators in all positions between operands
     for ops in itertools.product(operators, repeat=len(operands)-1):
+        # calculate left-to-right
         result = operands[0]
         for i, op in enumerate(ops):
             result = op(result, operands[i+1])
 
         # print(f"{target}: {operands} -> {result} | {ops}")
 
+        # return early if we find a calculation that works
         if result == target:
             return target
+
+    # no valid calculation found
     return 0
 
 
+# concatenate two ints as if they were strings
 def concat(l: int, r: int) -> int:
     return int(f"{l}{r}")
 
@@ -25,15 +32,18 @@ def main():
 
     total = 0
     p2total = 0
+
     for line in inputs:
         target, operands = line.split(': ')
         target = int(target)
         operands = list(map(int, operands.split(' ')))
 
         result = calibrate(target, operands, [operator.add, operator.mul])
         total += result
+
         if result == 0:
             p2total += calibrate(target, operands, [operator.add, operator.mul, concat])
+
     print(f"p1: {total}")
     print(f"p2: {total+p2total}")