Project Euler Q38 - LO Man Hei

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    "### Q38\n",
    "What is the largest 1 to 9 pandigital 9-digit number that can be formed as the concatenated product of an integer with \\((1,2, … ,n)\\) where \\(n > 1\\)?"
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    "def is_pandigital(num_string):\n",
    "    return sorted(num_string) == [str(n) for n in range(1,10)]\n",
    "    \n",
    "def unique_digit_num(n, selected_digits = None, candidate_digits = None):\n",
    "    if selected_digits is None and candidate_digits is None:\n",
    "        selected_digits = []\n",
    "        candidate_digits = list(range(1,10))\n",
    "    if n == 0:\n",
    "        return [int(''.join(str(i) for i in selected_digits))]\n",
    "    result = []\n",
    "    for i in range(len(candidate_digits)):\n",
    "        temp_candidate_digits = candidate_digits.copy()\n",
    "        result += unique_digit_num(n-1,selected_digits+[temp_candidate_digits.pop(i)],temp_candidate_digits)\n",
    "    return result\n",
    "\n",
    "def largest_pandigital_multiples():\n",
    "    for a in unique_digit_num(4,[],[2,3,4,5,6,7,9])[::-1]:\n",
    "        b = a*2\n",
    "        str_ab = str(a)+str(b)\n",
    "        if is_pandigital(str_ab):\n",
    "            return int(str_ab)"
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      "CPU times: user 673 µs, sys: 181 µs, total: 854 µs\n",
      "Wall time: 855 µs\n"
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   "source": [
    "%%time\n",
    "largest_pandigital_multiples()"
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