iterative solution

Author: zedrdave

2018/Playground.ipynb

@@ -2,7 +2,7 @@
  "cells": [
   {
    "cell_type": "code",
-   "execution_count": 117,
+   "execution_count": 45,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -15,11 +15,11 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 101,
+   "execution_count": 20,
    "metadata": {},
    "outputs": [],
    "source": [
-    "# data = \"2 3 0 3 10 11 12 1 1 0 1 99 2 1 1 2\""
+    "data = \"2 3 0 3 10 11 12 1 1 0 1 99 2 1 1 2\""
    ]
   },
   {
@@ -112,6 +112,135 @@
     "print(f\"Part 2:\", tree.part_2())"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": 21,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Part 1: 138\n"
+     ]
+    }
+   ],
+   "source": [
+    "def iter_process(N):\n",
+    "    stack = []\n",
+    "    meta = []\n",
+    "    stack.append(N[:2])\n",
+    "    N = N[2:]\n",
+    "\n",
+    "    while len(stack):\n",
+    "        if stack[-1][0] == 0:\n",
+    "            _, num_meta = stack.pop()\n",
+    "            meta += N[:num_meta]\n",
+    "            N = N[num_meta:]\n",
+    "        else:\n",
+    "            stack[-1][0] -= 1\n",
+    "            stack.append(N[:2])\n",
+    "            N = N[2:]\n",
+    "            \n",
+    "    print('Part 1:', sum(meta))\n",
+    "    \n",
+    "iter_process(list(map(int, data.split())))"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 80,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Part 1: 36566\n",
+      "Part 2: 30548\n"
+     ]
+    }
+   ],
+   "source": [
+    "def iter_process(N, part):\n",
+    "    num_nodes, num_meta, *N = N\n",
+    "    stack = [[num_nodes, num_meta, []]]\n",
+    "\n",
+    "    while True:\n",
+    "        if stack[-1][0] == 0:\n",
+    "            _, num_meta, meta = stack.pop()\n",
+    "            \n",
+    "            if part == 1:\n",
+    "                tot = sum(meta) + sum(N[:num_meta])\n",
+    "            elif part == 2:\n",
+    "                tot = sum([meta[i-1] for i in N[:num_meta] if 0 < i <= len(meta)])\n",
+    "            \n",
+    "            if not len(stack):\n",
+    "                return tot\n",
+    "            \n",
+    "            stack[-1][2].append(tot)\n",
+    "            N = N[num_meta:]\n",
+    "        else:\n",
+    "            stack[-1][0] -= 1\n",
+    "            num_nodes, num_meta, *N = N\n",
+    "\n",
+    "            if num_nodes == 0:\n",
+    "                stack[-1][2].append(sum(N[:num_meta]))\n",
+    "                N = N[num_meta:]\n",
+    "            else:\n",
+    "                stack.append([num_nodes, num_meta, []])\n",
+    "            \n",
+    "    \n",
+    "print(\"Part 1:\", iter_process(map(int, data.split()), part=1))\n",
+    "print(\"Part 2:\", iter_process(map(int, data.split()), part=2))"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 106,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Part 1: 36566\n",
+      "Part 2: 30548\n"
+     ]
+    }
+   ],
+   "source": [
+    "# Factored-to-death version:\n",
+    "\n",
+    "def iter_process(N, part):\n",
+    "    stack = [[1, 0, []]]\n",
+    "    \n",
+    "    while True:\n",
+    "        if stack[-1][0]:\n",
+    "            stack[-1][0] -= 1\n",
+    "            num_nodes, num_meta, *N = N\n",
+    "            if num_nodes == 0:\n",
+    "                tot = sum(N[:num_meta])\n",
+    "        else:\n",
+    "            num_nodes, num_meta, meta = stack.pop()\n",
+    "            if not len(stack):\n",
+    "                return meta[0]            \n",
+    "            if part == 1:\n",
+    "                tot = sum(meta) + sum(N[:num_meta])\n",
+    "            elif part == 2:\n",
+    "                tot = sum(meta[i-1] for i in N[:num_meta] if 0 < i <= len(meta))\n",
+    "\n",
+    "        if num_nodes == 0:\n",
+    "            stack[-1][2].append(tot)\n",
+    "            N = N[num_meta:]\n",
+    "        else:\n",
+    "            stack.append([num_nodes, num_meta, []])\n",
+    "            \n",
+    "    \n",
+    "print(\"Part 1:\", iter_process(map(int, data.split()), part=1))\n",
+    "print(\"Part 2:\", iter_process(map(int, data.split()), part=2))"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,