{
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  {
   "cell_type": "markdown",
   "id": "92b94045-a058-4b99-bfb6-7709a2a96f1a",
   "metadata": {},
   "source": [
    "# Idea 1: O(n^2)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 27,
   "id": "764a6c5e-5fa8-41be-9ec2-2b097ed29af6",
   "metadata": {
    "tags": []
   },
   "outputs": [],
   "source": [
    "pub fn two_sum(nums: Vec<i32>, target: i32) -> Vec<i32> {\n",
    "    for (i, n) in nums.iter().enumerate() {\n",
    "        for (k, m) in nums.iter().enumerate() {\n",
    "            if i == k {\n",
    "                continue;\n",
    "            } else if n + m == target {\n",
    "                return vec![i as i32, k as i32];\n",
    "            }\n",
    "        }\n",
    "    }\n",
    "    vec![]\n",
    "}"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "4278ee69-8a33-480c-a33b-1049bcec1eed",
   "metadata": {},
   "source": [
    "# Idea 2: O(n)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 28,
   "id": "7ad2762a-1deb-46ce-93fb-84b6ef637951",
   "metadata": {
    "tags": []
   },
   "outputs": [],
   "source": [
    "use std::collections::HashMap;\n",
    "\n",
    "pub fn two_sum(nums: Vec<i32>, target: i32) -> Vec<i32> {\n",
    "    let mut hm = HashMap::<i32, i32>::new();\n",
    "    \n",
    "    for (i, n) in nums.into_iter().enumerate() {\n",
    "        if let Some(k) = hm.get(&(target - n)) {\n",
    "            return vec![*k, i as i32];\n",
    "        } else {\n",
    "            hm.insert(n, i as i32);\n",
    "        }\n",
    "    }\n",
    "    vec![]\n",
    "}"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "d14e0757-f7eb-4c52-aab7-53a47b707377",
   "metadata": {},
   "source": [
    "# Tests"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 29,
   "id": "8bdf4378-b7b4-4edb-a409-4e3f98517c41",
   "metadata": {
    "tags": []
   },
   "outputs": [],
   "source": [
    "assert_eq!(two_sum(vec![2,7,11,15], 9), vec![0,1]);\n",
    "assert_eq!(two_sum(vec![3,2,4], 6), vec![1,2]);\n",
    "assert_eq!(two_sum(vec![3,3], 6), vec![0,1]);"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "150230c1-b43b-4275-8be7-3f35761cb19f",
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
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   "file_extension": ".rs",
   "mimetype": "text/rust",
   "name": "Rust",
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