Add day 16 result

day-16/day-16.py

@@ -0,0 +1,114 @@
+#!/usr/bin/env python3
+from pathlib import Path
+from math import prod
+
+
+def get_next_packet(msg, start, packets, res=0):
+    idx = start
+    if (idx+11) >= len(msg):
+        idx = -1
+        return idx, res
+    version = int(msg[idx:idx + 3], 2)
+    idx += 3
+    res += version
+    type_id = int(msg[idx:idx + 3], 2)
+    idx += 3
+    payload = None
+    match type_id:
+        case 4:
+            # literal
+            end = False
+            literal = 0
+            while not end:
+                if not int(msg[idx:idx + 1], 2):
+                    end = True
+                idx += 1
+                literal = (literal << 4) | int(msg[idx:idx + 4], 2)
+                idx += 4
+            payload = literal
+            # print('l', version, type_id, literal)
+        case _:
+            length_id = int(msg[idx:idx + 1], 2)
+            idx += 1
+            length = 0
+            payload = []
+            if length_id:
+                length = int(msg[idx:idx + 11], 2)
+                idx += 11
+                # print('o', version, type_id, length_id, length)
+                for _ in range(length):
+                    idx, res = get_next_packet(msg, idx, payload, res)
+            else:
+                length = int(msg[idx:idx + 15], 2)
+                idx += 15
+                # print('o', version, type_id, length_id, length)
+                next_idx = idx + length
+                while idx < next_idx:
+                    idx, res = get_next_packet(msg, idx, payload, res)
+    packets.append({'version': version, 'type_id': type_id, 'payload': payload})
+    return idx, res
+
+
+def calc_result(packets):
+    res = 0
+    for p in packets:
+        match p['type_id']:
+            case 4:
+                res = p['payload']
+            case _:
+                sub_packets = []
+                for i in range(len(p['payload'])):
+                    sub_packets.append(calc_result([p['payload'][i]]))
+                match p['type_id']:
+                    case 0:
+                        res = sum(sub_packets)
+                    case 1:
+                        res = prod(sub_packets)
+                    case 2:
+                        res = min(sub_packets)
+                    case 3:
+                        res = max(sub_packets)
+                    case 5:
+                        res = 1 if sub_packets[0] > sub_packets[1] else 0
+                    case 6:
+                        res = 1 if sub_packets[0] < sub_packets[1] else 0
+                    case 7:
+                        res = 1 if sub_packets[0] == sub_packets[1] else 0
+    return res
+
+
+def part_1(input):
+    result = 0
+    line = input[0].rstrip().strip('0')
+    msg = bin(int(line, 16))
+    msg = msg[2:]
+    while len(msg) % 4:
+        msg = '0' + msg
+    packets = []
+    next = 0
+    while -1 != next:
+        next, result = get_next_packet(msg, next, packets, result)
+    print("Part 1 result:", result)
+
+
+def part_2(input):
+    result = 0
+    line = input[0].rstrip().strip('0')
+    msg = bin(int(line, 16))
+    msg = msg[2:]
+    while len(msg) % 4:
+        msg = '0' + msg
+    packets = []
+    next = 0
+    while -1 != next:
+        next, _ = get_next_packet(msg, next, packets)
+    result = calc_result(packets)
+    print("Part 2 result:", result)
+
+
+input = list()
+p = Path(__file__).with_name('input.txt')
+with open(p) as f:
+    input = f.readlines()
+    part_1(input)
+    part_2(input)