From f78fa5d772da2ba6440d7ab62a311537084d5c22 Mon Sep 17 00:00:00 2001
From: Marijn Doeve <marijn@doeve.me>
Date: Thu, 16 Dec 2021 19:52:17 +0100
Subject: [PATCH] Optimize 16

---
 16/16.py | 42 ++++++++++++++++--------------------------
 1 file changed, 16 insertions(+), 26 deletions(-)

diff --git a/16/16.py b/16/16.py
index 4fe51eb..a0e3b2d 100644
--- a/16/16.py
+++ b/16/16.py
@@ -1,8 +1,11 @@
 import sys
 from math import prod
+from typing import Callable
+
+operator_func = Callable[[list[int]], int]
 
 LITERAL = 4
-OPERATOR = {
+OPERATOR: dict[int, operator_func] = {
     0: sum,
     1: prod,
     2: min,
@@ -15,12 +18,12 @@ OPERATOR = {
 total_version = 0
 
 
-def read_bits(bits, start, n) -> tuple[str, int]:
+def read_bits(bits: str, start: int, n: int) -> tuple[str, int]:
     end = start + n
     return bits[start:end], end
 
 
-def read_bits_int(bits, start, n) -> tuple[int, int]:
+def read_bits_int(bits: str, start: int, n: int) -> tuple[int, int]:
     number_bits, pos = read_bits(bits, start, n)
     return int(number_bits, base=2), pos
 
@@ -33,33 +36,27 @@ def hex_string_to_bit_string(hex_string: str) -> str:
     return "".join([hex_to_bits(x) for x in list(hex_string)])
 
 
-def parse_packet(bits) -> int:
+def parse_packet(bits: str) -> tuple[int, int]:
     pos = 0
-    packet_version, _ = read_bits_int(bits, pos, 3)
+    packet_version, pos = read_bits_int(bits, pos, 3)
 
     global total_version
     total_version += packet_version
 
-    type_ID, _ = read_bits_int(bits[3:], pos, 3)
+    type_ID, pos = read_bits_int(bits, pos, 3)
 
     if type_ID == LITERAL:
-        # print("Found: literal")
         value, next_pos = parse_literal(bits[pos:])
-        # print("literal:", value)
     else:
-        # print("found: operator")
-        value, next_pos = parse_operator(bits[pos:])
+        value, next_pos = parse_operator(bits[pos:], type_ID)
 
     pos += next_pos
 
     return value, pos
 
 
-def parse_literal(bits) -> tuple[int, int]:
+def parse_literal(bits: str) -> tuple[int, int]:
     pos = 0
-    packet_version, pos = read_bits_int(bits, pos, 3)
-
-    type_ID, pos = read_bits_int(bits, pos, 3)
 
     number = ""
 
@@ -76,33 +73,26 @@ def parse_literal(bits) -> tuple[int, int]:
     return int(number, base=2), pos
 
 
-def parse_operator(bits) -> int:
-    pos = 0
-    packet_version, pos = read_bits_int(bits, pos, 3)
-    type_ID, pos = read_bits_int(bits, pos, 3)
+def parse_operator(bits: str, type_ID: int) -> tuple[int, int]:
+    length_type_id = bits[0]
 
-    length_type_id = bits[6]
-
-    pos = 7
+    pos = 1
 
     parts = []
 
     if length_type_id == "0":
         total_length, pos = read_bits_int(bits, pos, 15)
-        # print("total length:", total_length)
         read = 0
 
         while read != total_length:
             value, just_read = parse_packet(bits[pos:])
             read += just_read
-            # print(f"Length was: {just_read}, total: {read} of {total_length}")
             pos += just_read
             parts.append(value)
     else:
         number_of_subs, pos = read_bits_int(bits, pos, 11)
-        # print("number of subs:", number_of_subs)
 
-        for i in range(number_of_subs):
+        for _ in range(number_of_subs):
             value, next_pos = parse_packet(bits[pos:])
             parts.append(value)
             pos += next_pos
@@ -116,7 +106,7 @@ if __name__ == "__main__":
     hex_string = sys.stdin.readline().strip()
     bits = hex_string_to_bit_string(hex_string)
 
-    value, _ = parse_operator(bits)
+    value, _ = parse_packet(bits)
 
     print("part one:", total_version)
     print("part two:", value)