010-summation-of-primes.ipynb

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    "# Summation of primes\n",
    "## Problem 10 \n",
    "\n",
    "<div class=\"problem_content\" role=\"problem\">\n",
    "<p>The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.</p>\n",
    "<p>Find the sum of all the primes below two million.</p>\n",
    "</div>"
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    "def primes(limit):\n",
    "    \"\"\"Sieve of Eratosthenes\"\"\"\n",
    "    # Initialize the primality list\n",
    "    a = [True] * limit                          \n",
    "    a[0] = a[1] = False\n",
    "\n",
    "    for (i, isprime) in enumerate(a):\n",
    "        if isprime:\n",
    "            yield i\n",
    "            # Mark multiples as non-prime\n",
    "            for n in xrange(i*i, limit, i):     \n",
    "                a[n] = False"
   ]
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   "source": [
    "def solve(limit):\n",
    "    return sum(primes(limit))"
   ]
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   "source": [
    "assert solve(10) == 17"
   ]
  },
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   "source": [
    "## Solution"
   ]
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    {
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       "142913828922"
      ]
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     "execution_count": 4,
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   ],
   "source": [
    "solve(2000000)"
   ]
  }
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