003-largest-prime-factor.ipynb

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    "# Largest prime factor\n",
    "## Problem 3 \n",
    "\n",
    "<div class=\"problem_content\" role=\"problem\">\n",
    "<p>The prime factors of 13195 are 5, 7, 13 and 29.</p>\n",
    "<p>What is the largest prime factor of the number 600851475143 ?</p>\n",
    "</div>"
   ]
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    "from math import sqrt\n",
    "\n",
    "def factorize(n, start=2):\n",
    "    p = start\n",
    "    while p <= sqrt(n):\n",
    "        q, r = divmod(n, p)\n",
    "        if r == 0:\n",
    "            return [p] + factorize(q, p)\n",
    "        p += 1\n",
    "    return [n]"
   ]
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   "source": [
    "assert factorize(13195) == [5, 7, 13, 29]"
   ]
  },
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   "execution_count": 3,
   "metadata": {
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   "outputs": [],
   "source": [
    "def solve():\n",
    "    return max(factorize(600851475143))"
   ]
  },
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   "source": [
    "## Solution"
   ]
  },
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    {
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      "text/plain": [
       "6857"
      ]
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     "execution_count": 4,
     "metadata": {},
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    }
   ],
   "source": [
    "solve()"
   ]
  }
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