Solution to problem 9 part 2 in Python

src/P9.py

@@ -1,3 +1,6 @@
+import sys
+from itertools import combinations
+
 # --- Day 9: Encoding Error ---
 
 # With your neighbor happily enjoying their video game, you turn your attention
@@ -73,24 +76,74 @@
 
 
 with open("files/P9.txt", "r") as f:
-    numbers = [code for code in f.read().strip().split("\n")]
+    numbers = [int(num) for num in f.read().strip().split("\n")]
-
-from itertools import combinations
 
 
-def part_1() -> None:
+def part_1() -> int:
     window = 25
     for i in range(window, len(numbers)):
         if all(
             [
-                int(x) + int(y) != int(numbers[i])
+                x + y != numbers[i]
                 for x, y in combinations(numbers[i - window : i], 2)
             ]
         ):
             break
 
     print(f"The first number without the property is {numbers[i]}")
+    return numbers[i]
+
+
+# --- Part Two ---
+
+# The final step in breaking the XMAS encryption relies on the invalid number
+# you just found: you must find a contiguous set of at least two numbers in
+# your list which sum to the invalid number from step 1.
+
+# Again consider the above example:
+
+# 35
+# 20
+# 15
+# 25
+# 47
+# 40
+# 62
+# 55
+# 65
+# 95
+# 102
+# 117
+# 150
+# 182
+# 127
+# 219
+# 299
+# 277
+# 309
+# 576
+
+# In this list, adding up all of the numbers from 15 through 40 produces the
+# invalid number from step 1, 127. (Of course, the contiguous set of numbers in
+# your actual list might be much longer.)
+
+# To find the encryption weakness, add together the smallest and largest number
+# in this contiguous range; in this example, these are 15 and 47, producing 62.
+
+# What is the encryption weakness in your XMAS-encrypted list of numbers?
+
+
+def part_2() -> None:
+    target = invalid_number
+    for i in range(len(numbers)):
+        for j in range(i + 1, len(numbers)):
+            if sum(numbers[i:j]) == target:
+                print(
+                    f"The encryption weakness is {min(numbers[i:j]) + max(numbers[i:j])}"
+                )
+                return
 
 
 if __name__ == "__main__":
-    part_1()
+    invalid_number = part_1()
+    part_2()