From 7da0981cc5190bca778693dc567d930bb4174cd4 Mon Sep 17 00:00:00 2001
From: Pascal Lais <pascal@lais.dev>
Date: Thu, 16 Dec 2021 08:54:57 +0100
Subject: [PATCH] Add day 16 result

---
 day-16/day-16.py | 114 +++++++++++++++++++++++++++++++++++++++++++++++
 day-16/input.txt |   1 +
 2 files changed, 115 insertions(+)
 create mode 100644 day-16/day-16.py
 create mode 100644 day-16/input.txt

diff --git a/day-16/day-16.py b/day-16/day-16.py
new file mode 100644
index 0000000..ec37279
--- /dev/null
+++ b/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)
diff --git a/day-16/input.txt b/day-16/input.txt
new file mode 100644
index 0000000..f6d6fd6
--- /dev/null
+++ b/day-16/input.txt
@@ -0,0 +1 @@
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