Project Euler Q23 - LO Man Hei

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   "source": [
    "### Q23\n",
    "Find the sum of all the positive integers which cannot be written as the sum of two abundant numbers."
   ]
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    "def divisors(n):\n",
    "    divs = []\n",
    "    for i in range(1,int((n)**(1/2))+1):\n",
    "        if n%i == 0:\n",
    "            divs.append(i)\n",
    "            divs.append(n//i)\n",
    "    return list(set(divs))\n",
    "\n",
    "def d(n):\n",
    "    return sum(divisors(n))-n\n",
    "\n",
    "def sum_non_abundant_nums(max_range,exclude_end = False):\n",
    "    if exclude_end:\n",
    "        max_range -= 1\n",
    "    abundant_nums_list = set()\n",
    "    result = (1 + max_range) * max_range // 2\n",
    "    for i in range(1,max_range+1):\n",
    "        if d(i) > i:\n",
    "            abundant_nums_list.add(i)\n",
    "        for j in abundant_nums_list:\n",
    "            if (i-j) in abundant_nums_list:\n",
    "                result -= i\n",
    "                break\n",
    "    return result"
   ]
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     "text": [
      "CPU times: user 224 ms, sys: 0 ns, total: 224 ms\n",
      "Wall time: 222 ms\n"
     ]
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       "4179871"
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     "execution_count": 28,
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   "source": [
    "%%time\n",
    "sum_non_abundant_nums(28123)"
   ]
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   "id": "64e99ccb-244e-4ffc-b1ff-f6012c715019",
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   "source": []
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