euler55.ipynb

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  15      "metadata": {},
  16      "output_type": "execute_result"
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  18    ],
  19    "source": [
  20     "load 'array-numbers.rb'"
  21    ]
  22   },
  23   {
  24    "cell_type": "code",
  25    "execution_count": 25,
  26    "metadata": {},
  27    "outputs": [
  28     {
  29      "data": {
  30       "text/plain": [
  31        ":lychrel?"
  32       ]
  33      },
  34      "execution_count": 25,
  35      "metadata": {},
  36      "output_type": "execute_result"
  37     }
  38    ],
  39    "source": [
  40     "class Integer\n",
  41     "  # Split a number into a list of digits\n",
  42     "  def palindrome?\n",
  43     "    self.to_s == self.to_s.reverse\n",
  44     "  end\n",
  45     "  \n",
  46     "  def lychrel_step\n",
  47     "    self + self.to_s.reverse.to_i\n",
  48     "  end\n",
  49     "  \n",
  50     "  def lychrel?(limit=50)\n",
  51     "    if lychrel_step.palindrome?\n",
  52     "      false\n",
  53     "    elsif limit == 0\n",
  54     "      true\n",
  55     "    else\n",
  56     "      lychrel_step.lychrel?(limit-1)\n",
  57     "    end\n",
  58     "  end\n",
  59     "end "
  60    ]
  61   },
  62   {
  63    "cell_type": "code",
  64    "execution_count": 27,
  65    "metadata": {},
  66    "outputs": [
  67     {
  68      "data": {
  69       "text/plain": [
  70        "true"
  71       ]
  72      },
  73      "execution_count": 27,
  74      "metadata": {},
  75      "output_type": "execute_result"
  76     }
  77    ],
  78    "source": [
  79     "7.palindrome?"
  80    ]
  81   },
  82   {
  83    "cell_type": "code",
  84    "execution_count": 28,
  85    "metadata": {},
  86    "outputs": [
  87     {
  88      "data": {
  89       "text/plain": [
  90        "true"
  91       ]
  92      },
  93      "execution_count": 28,
  94      "metadata": {},
  95      "output_type": "execute_result"
  96     }
  97    ],
  98    "source": [
  99     "717.palindrome?"
 100    ]
 101   },
 102   {
 103    "cell_type": "code",
 104    "execution_count": 29,
 105    "metadata": {},
 106    "outputs": [
 107     {
 108      "data": {
 109       "text/plain": [
 110        "121"
 111       ]
 112      },
 113      "execution_count": 29,
 114      "metadata": {},
 115      "output_type": "execute_result"
 116     }
 117    ],
 118    "source": [
 119     "47.lychrel_step"
 120    ]
 121   },
 122   {
 123    "cell_type": "code",
 124    "execution_count": 30,
 125    "metadata": {},
 126    "outputs": [
 127     {
 128      "data": {
 129       "text/plain": [
 130        "1292"
 131       ]
 132      },
 133      "execution_count": 30,
 134      "metadata": {},
 135      "output_type": "execute_result"
 136     }
 137    ],
 138    "source": [
 139     "349.lychrel_step"
 140    ]
 141   },
 142   {
 143    "cell_type": "code",
 144    "execution_count": 31,
 145    "metadata": {},
 146    "outputs": [
 147     {
 148      "data": {
 149       "text/plain": [
 150        "7337"
 151       ]
 152      },
 153      "execution_count": 31,
 154      "metadata": {},
 155      "output_type": "execute_result"
 156     }
 157    ],
 158    "source": [
 159     "349.lychrel_step.lychrel_step.lychrel_step"
 160    ]
 161   },
 162   {
 163    "cell_type": "code",
 164    "execution_count": 32,
 165    "metadata": {},
 166    "outputs": [
 167     {
 168      "data": {
 169       "text/plain": [
 170        "false"
 171       ]
 172      },
 173      "execution_count": 32,
 174      "metadata": {},
 175      "output_type": "execute_result"
 176     }
 177    ],
 178    "source": [
 179     "349.lychrel?"
 180    ]
 181   },
 182   {
 183    "cell_type": "code",
 184    "execution_count": 33,
 185    "metadata": {},
 186    "outputs": [
 187     {
 188      "data": {
 189       "text/plain": [
 190        "true"
 191       ]
 192      },
 193      "execution_count": 33,
 194      "metadata": {},
 195      "output_type": "execute_result"
 196     }
 197    ],
 198    "source": [
 199     "196.lychrel?"
 200    ]
 201   },
 202   {
 203    "cell_type": "code",
 204    "execution_count": 34,
 205    "metadata": {},
 206    "outputs": [
 207     {
 208      "data": {
 209       "text/plain": [
 210        "true"
 211       ]
 212      },
 213      "execution_count": 34,
 214      "metadata": {},
 215      "output_type": "execute_result"
 216     }
 217    ],
 218    "source": [
 219     "4994.lychrel?"
 220    ]
 221   },
 222   {
 223    "cell_type": "code",
 224    "execution_count": 35,
 225    "metadata": {},
 226    "outputs": [
 227     {
 228      "data": {
 229       "text/plain": [
 230        "249"
 231       ]
 232      },
 233      "execution_count": 35,
 234      "metadata": {},
 235      "output_type": "execute_result"
 236     }
 237    ],
 238    "source": [
 239     "(10...10**4).select {|n| n.lychrel?}.length"
 240    ]
 241   },
 242   {
 243    "cell_type": "code",
 244    "execution_count": null,
 245    "metadata": {
 246     "collapsed": true
 247    },
 248    "outputs": [],
 249    "source": []
 250   }
 251  ],
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 255    "language": "ruby",
 256    "name": "ruby"
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 267 }