Add day 13.

HoffmannChristian · HoffmannChristian · commit 44cd8c66447d · 2022-12-15T17:53:48.000+01:00
diff --git a/2022/advent_of_code_2022.ipynb b/2022/advent_of_code_2022.ipynb
@@ -268,10 +268,10 @@
     "\n",
     "        stacks_str.reverse()\n",
     "        for line in stacks_str:\n",
-    "            for stack_id in range(len(line)):\n",
-    "                if(line[stack_id] == '.'):\n",
+    "            for stack_id,item in enumerate(line):\n",
+    "                if(item == '.'):\n",
     "                    continue\n",
-    "                stacks[stack_id].append(line[stack_id])\n",
+    "                stacks[stack_id].append(item)\n",
     "        return stacks\n",
     "    \n",
     "    def parse_operations(operations_str):\n",
@@ -935,6 +935,83 @@
     "        num_steps = len(shortest_path)-1\n",
     "num_steps"
    ]
+  },
+  {
+   "attachments": {},
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Day 13: Distress Signal\n",
+    "\n",
+    "What is the sum of the indices of those pairs?"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "def to_list(value):\n",
+    "    return value if type(value) == list else [value]\n",
+    "\n",
+    "def check_list_order(left, right):\n",
+    "        if not left and not right:\n",
+    "           return 0\n",
+    "        if not left:\n",
+    "            return -1\n",
+    "        if not right:\n",
+    "            return 1\n",
+    "        if check_order(left[0], right[0]):\n",
+    "            return check_order(left[0], right[0])\n",
+    "        return check_order(left[1:], right[1:])\n",
+    "\n",
+    "def check_order(left, right):\n",
+    "    if (type(left), type(right)) == (int, int):\n",
+    "        return left - right\n",
+    "    return check_list_order(to_list(left), to_list(right))\n",
+    "\n",
+    "lines = open('13_input.txt', 'r').read().split('\\n\\n')\n",
+    "pairs = [[eval(pair_str) for pair_str in line.split()] for line in lines]\n",
+    "\n",
+    "idx_of_pairs_in_right_order = []\n",
+    "for pair_idx, (left, right) in enumerate(pairs, start=1):\n",
+    "    if check_order(left, right) < 0:\n",
+    "        idx_of_pairs_in_right_order.append(pair_idx)\n",
+    "\n",
+    "sum(idx_of_pairs_in_right_order)"
+   ]
+  },
+  {
+   "attachments": {},
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "What is the decoder key for the distress signal?"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from functools import cmp_to_key, reduce\n",
+    "from operator import mul\n",
+    "\n",
+    "def flatten(list_of_lists):\n",
+    "    '''Flatten one level of nesting in a list of lists.'''\n",
+    "    return [item for sublist in list_of_lists for item in sublist]\n",
+    "\n",
+    "divider_packets = [[[2]], [[6]]]\n",
+    "\n",
+    "pairs = flatten(pairs)\n",
+    "pairs.extend(divider_packets)\n",
+    "pairs = sorted(pairs, key=cmp_to_key(check_order))\n",
+    "\n",
+    "divider_packet_idx = [pairs.index(packet)+1 for packet in divider_packets]\n",
+    "reduce(mul, divider_packet_idx)"
+   ]
   }
  ],
  "metadata": {
