16!

16/16.py

@@ -0,0 +1,122 @@
+import sys
+from math import prod
+
+LITERAL = 4
+OPERATOR = {
+    0: sum,
+    1: prod,
+    2: min,
+    3: max,
+    5: lambda lst: int(lst[0] > lst[1]),
+    6: lambda lst: int(lst[0] < lst[1]),
+    7: lambda lst: int(lst[0] == lst[1]),
+}
+
+total_version = 0
+
+
+def read_bits(bits, start, n) -> tuple[str, int]:
+    end = start + n
+    return bits[start:end], end
+
+
+def read_bits_int(bits, start, n) -> tuple[int, int]:
+    number_bits, pos = read_bits(bits, start, n)
+    return int(number_bits, base=2), pos
+
+
+def hex_to_bits(hex: str) -> str:
+    return format(int(hex, base=16), "04b")
+
+
+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:
+    pos = 0
+    packet_version, _ = read_bits_int(bits, pos, 3)
+
+    global total_version
+    total_version += packet_version
+
+    type_ID, _ = read_bits_int(bits[3:], 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:])
+
+    pos += next_pos
+
+    return value, pos
+
+
+def parse_literal(bits) -> tuple[int, int]:
+    pos = 0
+    packet_version, pos = read_bits_int(bits, pos, 3)
+
+    type_ID, pos = read_bits_int(bits, pos, 3)
+
+    number = ""
+
+    done = False
+
+    while not done:
+        part, pos = read_bits(bits, pos, 5)
+
+        if part[0] == "0":
+            done = True
+
+        number += part[1:]
+
+    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)
+
+    length_type_id = bits[6]
+
+    pos = 7
+
+    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):
+            value, next_pos = parse_packet(bits[pos:])
+            parts.append(value)
+            pos += next_pos
+
+    calculated = OPERATOR[type_ID](parts)
+
+    return calculated, pos
+
+
+if __name__ == "__main__":
+    hex_string = sys.stdin.readline().strip()
+    bits = hex_string_to_bit_string(hex_string)
+
+    value, _ = parse_operator(bits)
+
+    print("part one:", total_version)
+    print("part two:", value)