{
 "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": 22,
   "id": "167e31a3-7844-4cdf-a563-241a40b07212",
   "metadata": {
    "tags": []
   },
   "outputs": [],
   "source": [
    "pub fn add_two_numbers(l1: Option<Box<ListNode>>, l2: Option<Box<ListNode>>) -> Option<Box<ListNode>> {\n",
    "    let mut carry = 0;\n",
    "    let mut res = None;\n",
    "    let mut p = &mut res;\n",
    "    let mut p1 = &l1;\n",
    "    let mut p2 = &l2;\n",
    "    \n",
    "    while p1.is_some() || p2.is_some() || carry > 0 {\n",
    "        let mut val = carry;\n",
    "        if let Some(ref n1) = p1 {\n",
    "            val += n1.val;\n",
    "            p1 = &n1.next;\n",
    "        }\n",
    "        if let Some(ref n2) = p2 {\n",
    "            val += n2.val;\n",
    "            p2 = &n2.next;\n",
    "        }\n",
    "        carry = val / 10;\n",
    "        *p = Some(Box::new(ListNode::new(val % 10)));\n",
    "        p = &mut p.as_mut().unwrap().next;\n",
    "    }\n",
    "    \n",
    "    res\n",
    "}"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "0f4e6fc2-0fd1-4789-b14f-4c49f5d7a96d",
   "metadata": {},
   "outputs": [],
   "source": []
  },
  {
   "cell_type": "markdown",
   "id": "f9dab3ca-0d78-4050-b94b-ad0d19348b09",
   "metadata": {},
   "source": [
    "# Test Utils"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "id": "33f9c78d-98f5-4d95-9ed0-e0c1961dc7b6",
   "metadata": {
    "tags": []
   },
   "outputs": [],
   "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": 23,
   "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": []
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "rust-Rust kernel",
   "language": "rust",
   "name": "rust-rust"
  },
  "language_info": {
   "codemirror_mode": "rust",
   "file_extension": ".rs",
   "mimetype": "text/rust",
   "name": "Rust",
   "pygment_lexer": "rust",
   "version": ""
  }
 },
 "nbformat": 4,
 "nbformat_minor": 5
}