euler30.ipynb

   1 {
   2  "cells": [
   3   {
   4    "cell_type": "code",
   5    "execution_count": 15,
   6    "metadata": {
   7     "collapsed": false
   8    },
   9    "outputs": [
  10     {
  11      "data": {
  12       "text/plain": [
  13        "Object"
  14       ]
  15      },
  16      "execution_count": 15,
  17      "metadata": {},
  18      "output_type": "execute_result"
  19     }
  20    ],
  21    "source": [
  22     "include Math"
  23    ]
  24   },
  25   {
  26    "cell_type": "code",
  27    "execution_count": 10,
  28    "metadata": {
  29     "collapsed": false
  30    },
  31    "outputs": [
  32     {
  33      "data": {
  34       "text/plain": [
  35        "642"
  36       ]
  37      },
  38      "execution_count": 10,
  39      "metadata": {},
  40      "output_type": "execute_result"
  41     }
  42    ],
  43    "source": [
  44     "125.to_s.each_char.map {|d| d.to_i ** 4}.sum"
  45    ]
  46   },
  47   {
  48    "cell_type": "code",
  49    "execution_count": 11,
  50    "metadata": {
  51     "collapsed": false
  52    },
  53    "outputs": [
  54     {
  55      "data": {
  56       "text/plain": [
  57        "1634"
  58       ]
  59      },
  60      "execution_count": 11,
  61      "metadata": {},
  62      "output_type": "execute_result"
  63     }
  64    ],
  65    "source": [
  66     "1634.to_s.each_char.map {|d| d.to_i ** 4}.sum"
  67    ]
  68   },
  69   {
  70    "cell_type": "code",
  71    "execution_count": 16,
  72    "metadata": {
  73     "collapsed": false
  74    },
  75    "outputs": [
  76     {
  77      "data": {
  78       "text/plain": [
  79        "5.470182551532643"
  80       ]
  81      },
  82      "execution_count": 16,
  83      "metadata": {},
  84      "output_type": "execute_result"
  85     }
  86    ],
  87    "source": [
  88     "log10(5) + 5 * log10(9)"
  89    ]
  90   },
  91   {
  92    "cell_type": "code",
  93    "execution_count": 18,
  94    "metadata": {
  95     "collapsed": false
  96    },
  97    "outputs": [
  98     {
  99      "name": "stdout",
 100      "output_type": "stream",
 101      "text": [
 102       "0: -Infinity =?= 1\n",
 103       "1: 4.771212547196624 =?= 2\n",
 104       "2: 5.0722425428606055 =?= 3\n",
 105       "3: 5.248333801916287 =?= 4\n",
 106       "4: 5.373272538524587 =?= 5\n",
 107       "5: 5.470182551532643 =?= 6\n",
 108       "6: 5.549363797580268 =?= 7\n",
 109       "7: 5.616310587210881 =?= 8\n",
 110       "8: 5.674302534188568 =?= 9\n",
 111       "9: 5.7254550566359494 =?= 10\n"
 112      ]
 113     },
 114     {
 115      "data": {
 116       "text/plain": [
 117        "10"
 118       ]
 119      },
 120      "execution_count": 18,
 121      "metadata": {},
 122      "output_type": "execute_result"
 123     }
 124    ],
 125    "source": [
 126     "10.times do |n|\n",
 127     "  puts \"#{n}: #{log10(n) + 5 * log10(9)} =?= #{n+1}\"\n",
 128     "end"
 129    ]
 130   },
 131   {
 132    "cell_type": "code",
 133    "execution_count": 19,
 134    "metadata": {
 135     "collapsed": false
 136    },
 137    "outputs": [
 138     {
 139      "data": {
 140       "text/plain": [
 141        ":digit_power_sum"
 142       ]
 143      },
 144      "execution_count": 19,
 145      "metadata": {},
 146      "output_type": "execute_result"
 147     }
 148    ],
 149    "source": [
 150     "def digit_power_sum(n, p)\n",
 151     "  n.to_s.each_char.map {|d| d.to_i ** p}.sum\n",
 152     "end"
 153    ]
 154   },
 155   {
 156    "cell_type": "code",
 157    "execution_count": null,
 158    "metadata": {
 159     "collapsed": true
 160    },
 161    "outputs": [],
 162    "source": [
 163     "(2..10^6)"
 164    ]
 165   },
 166   {
 167    "cell_type": "code",
 168    "execution_count": 20,
 169    "metadata": {
 170     "collapsed": false
 171    },
 172    "outputs": [
 173     {
 174      "data": {
 175       "text/plain": [
 176        "642"
 177       ]
 178      },
 179      "execution_count": 20,
 180      "metadata": {},
 181      "output_type": "execute_result"
 182     }
 183    ],
 184    "source": [
 185     "digit_power_sum(125, 4)"
 186    ]
 187   },
 188   {
 189    "cell_type": "code",
 190    "execution_count": 21,
 191    "metadata": {
 192     "collapsed": false
 193    },
 194    "outputs": [
 195     {
 196      "data": {
 197       "text/plain": [
 198        "1634"
 199       ]
 200      },
 201      "execution_count": 21,
 202      "metadata": {},
 203      "output_type": "execute_result"
 204     }
 205    ],
 206    "source": [
 207     "digit_power_sum(1634, 4)"
 208    ]
 209   },
 210   {
 211    "cell_type": "code",
 212    "execution_count": 23,
 213    "metadata": {
 214     "collapsed": false
 215    },
 216    "outputs": [
 217     {
 218      "data": {
 219       "text/plain": [
 220        "[1634, 8208, 9474]"
 221       ]
 222      },
 223      "execution_count": 23,
 224      "metadata": {},
 225      "output_type": "execute_result"
 226     }
 227    ],
 228    "source": [
 229     "(2..10000).select {|n| digit_power_sum(n, 4) == n}"
 230    ]
 231   },
 232   {
 233    "cell_type": "code",
 234    "execution_count": 32,
 235    "metadata": {
 236     "collapsed": false
 237    },
 238    "outputs": [
 239     {
 240      "data": {
 241       "text/plain": [
 242        "[1, 4150, 4151, 54748, 92727, 93084, 194979]"
 243       ]
 244      },
 245      "execution_count": 32,
 246      "metadata": {},
 247      "output_type": "execute_result"
 248     }
 249    ],
 250    "source": [
 251     "(1..10**6).select {|n| digit_power_sum(n, 5) == n}"
 252    ]
 253   },
 254   {
 255    "cell_type": "code",
 256    "execution_count": 33,
 257    "metadata": {
 258     "collapsed": false
 259    },
 260    "outputs": [
 261     {
 262      "data": {
 263       "text/plain": [
 264        "[1, 4150, 4151, 54748, 92727, 93084, 194979]"
 265       ]
 266      },
 267      "execution_count": 33,
 268      "metadata": {},
 269      "output_type": "execute_result"
 270     }
 271    ],
 272    "source": [
 273     "(1..10**7).select {|n| digit_power_sum(n, 5) == n}"
 274    ]
 275   },
 276   {
 277    "cell_type": "code",
 278    "execution_count": 34,
 279    "metadata": {
 280     "collapsed": false
 281    },
 282    "outputs": [
 283     {
 284      "data": {
 285       "text/plain": [
 286        "443839"
 287       ]
 288      },
 289      "execution_count": 34,
 290      "metadata": {},
 291      "output_type": "execute_result"
 292     }
 293    ],
 294    "source": [
 295     "(2..10**6).select {|n| digit_power_sum(n, 5) == n}.sum"
 296    ]
 297   },
 298   {
 299    "cell_type": "code",
 300    "execution_count": null,
 301    "metadata": {
 302     "collapsed": true
 303    },
 304    "outputs": [],
 305    "source": []
 306   }
 307  ],
 308  "metadata": {
 309   "kernelspec": {
 310    "display_name": "Ruby 2.4.0",
 311    "language": "ruby",
 312    "name": "ruby"
 313   },
 314   "language_info": {
 315    "file_extension": ".rb",
 316    "mimetype": "application/x-ruby",
 317    "name": "ruby",
 318    "version": "2.4.0"
 319   }
 320  },
 321  "nbformat": 4,
 322  "nbformat_minor": 0
 323 }