Add function that size of the smallest directory that should be deleted

puzzles/solutions/2022/d07/p2.py

@@ -1,8 +1,18 @@
 import sys
 
+import consts
+import p1
+
 
 def get_answer(input_text: str):
-    raise NotImplementedError
+    """Return total size of the smallest directory that, if deleted, would free up enough space on the filesystem."""
+    filesystem = p1.get_filesystem(input_text)
+    root = filesystem[0]
+    total_used_space = root.size
+    unused_space_needed = consts.REQUIRED_UNUSED_SPACE -(consts.TOTAL_DISK_SPACE - total_used_space)
+    candidate_directories = (directory for directory in filesystem if directory.size >= unused_space_needed)
+    directory_to_delete = min(candidate_directories, key=lambda directory: directory.size)
+    return directory_to_delete.size
 
 
 if __name__ == "__main__":