euler47.ipynb

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  10     {
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  13        "true"
  14       ]
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  16      "execution_count": 2,
  17      "metadata": {},
  18      "output_type": "execute_result"
  19     }
  20    ],
  21    "source": [
  22     "load 'divisors.rb'"
  23    ]
  24   },
  25   {
  26    "cell_type": "code",
  27    "execution_count": 3,
  28    "metadata": {
  29     "collapsed": false
  30    },
  31    "outputs": [
  32     {
  33      "data": {
  34       "text/plain": [
  35        "{3=>1, 5=>1}"
  36       ]
  37      },
  38      "execution_count": 3,
  39      "metadata": {},
  40      "output_type": "execute_result"
  41     }
  42    ],
  43    "source": [
  44     "15.prime_factors"
  45    ]
  46   },
  47   {
  48    "cell_type": "code",
  49    "execution_count": 5,
  50    "metadata": {
  51     "collapsed": false
  52    },
  53    "outputs": [
  54     {
  55      "data": {
  56       "text/plain": [
  57        "3"
  58       ]
  59      },
  60      "execution_count": 5,
  61      "metadata": {},
  62      "output_type": "execute_result"
  63     }
  64    ],
  65    "source": [
  66     "644.prime_factors.length"
  67    ]
  68   },
  69   {
  70    "cell_type": "code",
  71    "execution_count": 10,
  72    "metadata": {
  73     "collapsed": false
  74    },
  75    "outputs": [
  76     {
  77      "data": {
  78       "text/plain": [
  79        ":k_prime_factors"
  80       ]
  81      },
  82      "execution_count": 10,
  83      "metadata": {},
  84      "output_type": "execute_result"
  85     }
  86    ],
  87    "source": [
  88     "def k_prime_factors(n, k)\n",
  89     "  (n...(n+k)).all? {|i| i.prime_factors.length == k}\n",
  90     "end"
  91    ]
  92   },
  93   {
  94    "cell_type": "code",
  95    "execution_count": 6,
  96    "metadata": {
  97     "collapsed": false
  98    },
  99    "outputs": [
 100     {
 101      "data": {
 102       "text/plain": [
 103        ":sequence"
 104       ]
 105      },
 106      "execution_count": 6,
 107      "metadata": {},
 108      "output_type": "execute_result"
 109     }
 110    ],
 111    "source": [
 112     "def sequence(&generator)\n",
 113     "  Enumerator.new do |yielder|\n",
 114     "    n = 0\n",
 115     "    loop do\n",
 116     "      yielder.yield generator.call(n)\n",
 117     "      n = n + 1\n",
 118     "    end\n",
 119     "  end\n",
 120     "end"
 121    ]
 122   },
 123   {
 124    "cell_type": "code",
 125    "execution_count": 11,
 126    "metadata": {
 127     "collapsed": false
 128    },
 129    "outputs": [
 130     {
 131      "data": {
 132       "text/plain": [
 133        "#<Enumerator: #<Enumerator::Generator:0x00557286d6e4c8>:each>"
 134       ]
 135      },
 136      "execution_count": 11,
 137      "metadata": {},
 138      "output_type": "execute_result"
 139     }
 140    ],
 141    "source": [
 142     "integers = sequence {|i| i}"
 143    ]
 144   },
 145   {
 146    "cell_type": "code",
 147    "execution_count": 14,
 148    "metadata": {
 149     "collapsed": false
 150    },
 151    "outputs": [
 152     {
 153      "data": {
 154       "text/plain": [
 155        "[14]"
 156       ]
 157      },
 158      "execution_count": 14,
 159      "metadata": {},
 160      "output_type": "execute_result"
 161     }
 162    ],
 163    "source": [
 164     "integers.lazy.select {|i| k_prime_factors(i, 2)}.take(1).force"
 165    ]
 166   },
 167   {
 168    "cell_type": "code",
 169    "execution_count": 13,
 170    "metadata": {
 171     "collapsed": false
 172    },
 173    "outputs": [
 174     {
 175      "data": {
 176       "text/plain": [
 177        "[644]"
 178       ]
 179      },
 180      "execution_count": 13,
 181      "metadata": {},
 182      "output_type": "execute_result"
 183     }
 184    ],
 185    "source": [
 186     "integers.lazy.select {|i| k_prime_factors(i, 3)}.take(1).force"
 187    ]
 188   },
 189   {
 190    "cell_type": "code",
 191    "execution_count": 15,
 192    "metadata": {
 193     "collapsed": false
 194    },
 195    "outputs": [
 196     {
 197      "data": {
 198       "text/plain": [
 199        "[134043]"
 200       ]
 201      },
 202      "execution_count": 15,
 203      "metadata": {},
 204      "output_type": "execute_result"
 205     }
 206    ],
 207    "source": [
 208     "integers.lazy.select {|i| k_prime_factors(i, 4)}.take(1).force"
 209    ]
 210   },
 211   {
 212    "cell_type": "code",
 213    "execution_count": null,
 214    "metadata": {
 215     "collapsed": true
 216    },
 217    "outputs": [],
 218    "source": []
 219   }
 220  ],
 221  "metadata": {
 222   "kernelspec": {
 223    "display_name": "Ruby 2.4.0",
 224    "language": "ruby",
 225    "name": "ruby"
 226   },
 227   "language_info": {
 228    "file_extension": ".rb",
 229    "mimetype": "application/x-ruby",
 230    "name": "ruby",
 231    "version": "2.4.0"
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 233  },
 234  "nbformat": 4,
 235  "nbformat_minor": 0
 236 }