{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "feab2236-6685-4f83-9d50-054bf952f66e",
   "metadata": {
    "tags": []
   },
   "outputs": [],
   "source": [
    "// Definition for singly-linked list.\n",
    "#[derive(PartialEq, Eq, Clone, Debug)]\n",
    "pub struct ListNode {\n",
    "    pub val: i32,\n",
    "    pub next: Option<Box<ListNode>>\n",
    "}\n",
    "\n",
    "impl ListNode {\n",
    "    #[inline]\n",
    "    fn new(val: i32) -> Self {\n",
    "        ListNode {\n",
    "            next: None,\n",
    "            val\n",
    "        }\n",
    "    }\n",
    "}"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "65dd529b-49f6-4a98-b69d-12871b081a40",
   "metadata": {},
   "source": [
    "# Idea 1: O(n + m)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 23,
   "id": "167e31a3-7844-4cdf-a563-241a40b07212",
   "metadata": {
    "tags": []
   },
   "outputs": [],
   "source": [
    "pub fn internal_add_two_numbers(carry: i32, l1: Option<Box<ListNode>>, l2: Option<Box<ListNode>>) -> Option<Box<ListNode>> {\n",
    "    match (carry, l1, l2) {\n",
    "        (0, None, None) => None,\n",
    "        (_, l1, l2) => {\n",
    "            let mut new_val = carry;\n",
    "            if let Some(ref n1) = l1 {\n",
    "                new_val += n1.val;\n",
    "            }\n",
    "            if let Some(ref n2) = l2 {\n",
    "                new_val += n2.val;\n",
    "            }\n",
    "            let mut nn = ListNode::new(new_val % 10);\n",
    "            let carry = if new_val > 9 { 1 } else { 0 };\n",
    "            nn.next = internal_add_two_numbers(\n",
    "                carry,\n",
    "                l1.and_then(|n1| n1.next),\n",
    "                l2.and_then(|n2| n2.next)\n",
    "            );\n",
    "            Some(Box::new(nn))\n",
    "        }\n",
    "    }\n",
    "}\n",
    "\n",
    "pub fn add_two_numbers(l1: Option<Box<ListNode>>, l2: Option<Box<ListNode>>) -> Option<Box<ListNode>> {\n",
    "    internal_add_two_numbers(0, l1, l2)\n",
    "}"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "f9dab3ca-0d78-4050-b94b-ad0d19348b09",
   "metadata": {},
   "source": [
    "# Test Utils"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 24,
   "id": "33f9c78d-98f5-4d95-9ed0-e0c1961dc7b6",
   "metadata": {
    "tags": []
   },
   "outputs": [
    {
     "ename": "Error",
     "evalue": "duplicate definitions with name `with_next`",
     "output_type": "error",
     "traceback": [
      "\u001b[31m[E0592] Error:\u001b[0m duplicate definitions with name `with_next`",
      "   \u001b[38;5;246m╭\u001b[0m\u001b[38;5;246m─\u001b[0m\u001b[38;5;246m[\u001b[0mcommand_24:1:1\u001b[38;5;246m]\u001b[0m",
      "   \u001b[38;5;246m│\u001b[0m",
      " \u001b[38;5;246m3 │\u001b[0m \u001b[38;5;249m \u001b[0m\u001b[38;5;249m \u001b[0m\u001b[38;5;249m \u001b[0m\u001b[38;5;249m \u001b[0m\u001b[38;5;54mf\u001b[0m\u001b[38;5;54mn\u001b[0m\u001b[38;5;54m \u001b[0m\u001b[38;5;54mw\u001b[0m\u001b[38;5;54mi\u001b[0m\u001b[38;5;54mt\u001b[0m\u001b[38;5;54mh\u001b[0m\u001b[38;5;54m_\u001b[0m\u001b[38;5;54mn\u001b[0m\u001b[38;5;54me\u001b[0m\u001b[38;5;54mx\u001b[0m\u001b[38;5;54mt\u001b[0m\u001b[38;5;54m(\u001b[0m\u001b[38;5;54mv\u001b[0m\u001b[38;5;54ma\u001b[0m\u001b[38;5;54ml\u001b[0m\u001b[38;5;54m:\u001b[0m\u001b[38;5;54m \u001b[0m\u001b[38;5;54mi\u001b[0m\u001b[38;5;54m3\u001b[0m\u001b[38;5;54m2\u001b[0m\u001b[38;5;54m,\u001b[0m\u001b[38;5;54m \u001b[0m\u001b[38;5;54mn\u001b[0m\u001b[38;5;54me\u001b[0m\u001b[38;5;54mx\u001b[0m\u001b[38;5;54mt\u001b[0m\u001b[38;5;54m:\u001b[0m\u001b[38;5;54m \u001b[0m\u001b[38;5;54mL\u001b[0m\u001b[38;5;54mi\u001b[0m\u001b[38;5;54ms\u001b[0m\u001b[38;5;54mt\u001b[0m\u001b[38;5;54mN\u001b[0m\u001b[38;5;54mo\u001b[0m\u001b[38;5;54md\u001b[0m\u001b[38;5;54me\u001b[0m\u001b[38;5;54m)\u001b[0m\u001b[38;5;54m \u001b[0m\u001b[38;5;54m-\u001b[0m\u001b[38;5;54m>\u001b[0m\u001b[38;5;54m \u001b[0m\u001b[38;5;54mS\u001b[0m\u001b[38;5;54me\u001b[0m\u001b[38;5;54ml\u001b[0m\u001b[38;5;54mf\u001b[0m\u001b[38;5;249m \u001b[0m\u001b[38;5;249m{\u001b[0m",
      " \u001b[38;5;246m  ·\u001b[0m     \u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m┬\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m  ",
      " \u001b[38;5;246m  ·\u001b[0m                            \u001b[38;5;54m╰\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m other definition for `with_next`",
      "\u001b[38;5;246m───╯\u001b[0m"
     ]
    },
    {
     "ename": "Error",
     "evalue": "duplicate definitions with name `fromVec`",
     "output_type": "error",
     "traceback": [
      "\u001b[31m[E0592] Error:\u001b[0m duplicate definitions with name `fromVec`",
      "    \u001b[38;5;246m╭\u001b[0m\u001b[38;5;246m─\u001b[0m\u001b[38;5;246m[\u001b[0mcommand_24:1:1\u001b[38;5;246m]\u001b[0m",
      "    \u001b[38;5;246m│\u001b[0m",
      " \u001b[38;5;246m10 │\u001b[0m \u001b[38;5;249m \u001b[0m\u001b[38;5;249m \u001b[0m\u001b[38;5;249m \u001b[0m\u001b[38;5;249m \u001b[0m\u001b[38;5;54mf\u001b[0m\u001b[38;5;54mn\u001b[0m\u001b[38;5;54m \u001b[0m\u001b[38;5;54mf\u001b[0m\u001b[38;5;54mr\u001b[0m\u001b[38;5;54mo\u001b[0m\u001b[38;5;54mm\u001b[0m\u001b[38;5;54mV\u001b[0m\u001b[38;5;54me\u001b[0m\u001b[38;5;54mc\u001b[0m\u001b[38;5;54m(\u001b[0m\u001b[38;5;54mv\u001b[0m\u001b[38;5;54m:\u001b[0m\u001b[38;5;54m \u001b[0m\u001b[38;5;54mV\u001b[0m\u001b[38;5;54me\u001b[0m\u001b[38;5;54mc\u001b[0m\u001b[38;5;54m<\u001b[0m\u001b[38;5;54mi\u001b[0m\u001b[38;5;54m3\u001b[0m\u001b[38;5;54m2\u001b[0m\u001b[38;5;54m>\u001b[0m\u001b[38;5;54m)\u001b[0m\u001b[38;5;54m \u001b[0m\u001b[38;5;54m-\u001b[0m\u001b[38;5;54m>\u001b[0m\u001b[38;5;54m \u001b[0m\u001b[38;5;54mO\u001b[0m\u001b[38;5;54mp\u001b[0m\u001b[38;5;54mt\u001b[0m\u001b[38;5;54mi\u001b[0m\u001b[38;5;54mo\u001b[0m\u001b[38;5;54mn\u001b[0m\u001b[38;5;54m<\u001b[0m\u001b[38;5;54mB\u001b[0m\u001b[38;5;54mo\u001b[0m\u001b[38;5;54mx\u001b[0m\u001b[38;5;54m<\u001b[0m\u001b[38;5;54mS\u001b[0m\u001b[38;5;54me\u001b[0m\u001b[38;5;54ml\u001b[0m\u001b[38;5;54mf\u001b[0m\u001b[38;5;54m>\u001b[0m\u001b[38;5;54m>\u001b[0m\u001b[38;5;249m \u001b[0m\u001b[38;5;249m{\u001b[0m",
      " \u001b[38;5;246m   ·\u001b[0m     \u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m┬\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m  ",
      " \u001b[38;5;246m   ·\u001b[0m                           \u001b[38;5;54m╰\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m\u001b[38;5;54m─\u001b[0m other definition for `fromVec`",
      "\u001b[38;5;246m────╯\u001b[0m"
     ]
    }
   ],
   "source": [
    "impl ListNode {\n",
    "    #[inline]\n",
    "    fn with_next(val: i32, next: ListNode) -> Self {\n",
    "        ListNode {\n",
    "            next: Some(Box::new(next)),\n",
    "            val,\n",
    "        }\n",
    "    }\n",
    "    \n",
    "    fn fromVec(v: Vec<i32>) -> Option<Box<Self>> {\n",
    "        v.into_iter()\n",
    "            .rev()\n",
    "            .fold(None, |acc, val| {\n",
    "                match acc {\n",
    "                    None => Some(Box::new(ListNode::new(val))),\n",
    "                    Some(node) => Some(Box::new(ListNode::with_next(val, *node)))\n",
    "                }\n",
    "            })\n",
    "    }\n",
    "}\n",
    "\n",
    "assert_eq!(\n",
    "    ListNode::fromVec(vec![7, 0, 8]),\n",
    "    Some(Box::new(ListNode::with_next(7, ListNode::with_next(0, ListNode::new(8)))))\n",
    ");"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "69eca992-8fc9-4507-b636-d64b5561be21",
   "metadata": {},
   "source": [
    "# Test Cases"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "id": "30adc3ca-7327-4336-b294-3e8fd3380c01",
   "metadata": {
    "tags": []
   },
   "outputs": [],
   "source": [
    "assert_eq!(\n",
    "    add_two_numbers(\n",
    "        ListNode::fromVec(vec![2,4,3]),\n",
    "        ListNode::fromVec(vec![5,6,4])\n",
    "    ),\n",
    "    ListNode::fromVec(vec![7,0,8])\n",
    ");\n",
    "assert_eq!(\n",
    "    add_two_numbers(\n",
    "        ListNode::fromVec(vec![0]),\n",
    "        ListNode::fromVec(vec![0])\n",
    "    ),\n",
    "    ListNode::fromVec(vec![0])\n",
    ");\n",
    "\n",
    "assert_eq!(\n",
    "    add_two_numbers(\n",
    "        ListNode::fromVec(vec![9,9]),\n",
    "        ListNode::fromVec(vec![9])\n",
    "    ),\n",
    "    ListNode::fromVec(vec![8,0,1])\n",
    ");\n",
    "assert_eq!(\n",
    "    add_two_numbers(\n",
    "        ListNode::fromVec(vec![9,9,9,9,9,9,9]),\n",
    "        ListNode::fromVec(vec![9,9,9,9])\n",
    "    ),\n",
    "    ListNode::fromVec(vec![8,9,9,9,0,0,0,1])\n",
    ");"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "9377916a-51fc-4534-b53e-ec9ac5e3c81e",
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
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  "kernelspec": {
   "display_name": "rust-Rust kernel",
   "language": "rust",
   "name": "rust-rust"
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  "language_info": {
   "codemirror_mode": "rust",
   "file_extension": ".rs",
   "mimetype": "text/rust",
   "name": "Rust",
   "pygment_lexer": "rust",
   "version": ""
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 "nbformat": 4,
 "nbformat_minor": 5
}