euler36.ipynb

   1 {
   2  "cells": [
   3   {
   4    "cell_type": "code",
   5    "execution_count": 1,
   6    "metadata": {
   7     "collapsed": false
   8    },
   9    "outputs": [
  10     {
  11      "data": {
  12       "text/plain": [
  13        ":palindrome?"
  14       ]
  15      },
  16      "execution_count": 1,
  17      "metadata": {},
  18      "output_type": "execute_result"
  19     }
  20    ],
  21    "source": [
  22     "class String\n",
  23     "  def palindrome?\n",
  24     "    self.reverse == self\n",
  25     "  end\n",
  26     "end"
  27    ]
  28   },
  29   {
  30    "cell_type": "code",
  31    "execution_count": 2,
  32    "metadata": {
  33     "collapsed": false
  34    },
  35    "outputs": [
  36     {
  37      "data": {
  38       "text/plain": [
  39        "false"
  40       ]
  41      },
  42      "execution_count": 2,
  43      "metadata": {},
  44      "output_type": "execute_result"
  45     }
  46    ],
  47    "source": [
  48     "\"happy\".palindrome?"
  49    ]
  50   },
  51   {
  52    "cell_type": "code",
  53    "execution_count": 3,
  54    "metadata": {
  55     "collapsed": false
  56    },
  57    "outputs": [
  58     {
  59      "data": {
  60       "text/plain": [
  61        "true"
  62       ]
  63      },
  64      "execution_count": 3,
  65      "metadata": {},
  66      "output_type": "execute_result"
  67     }
  68    ],
  69    "source": [
  70     "\"abbacabba\".palindrome?"
  71    ]
  72   },
  73   {
  74    "cell_type": "code",
  75    "execution_count": 4,
  76    "metadata": {
  77     "collapsed": false
  78    },
  79    "outputs": [
  80     {
  81      "data": {
  82       "text/plain": [
  83        ":to_digits"
  84       ]
  85      },
  86      "execution_count": 4,
  87      "metadata": {},
  88      "output_type": "execute_result"
  89     }
  90    ],
  91    "source": [
  92     "class Integer\n",
  93     "  def to_digits(base=10)\n",
  94     "    self.to_s(base).split('').map {|d| d.to_i}\n",
  95     "  end\n",
  96     "end "
  97    ]
  98   },
  99   {
 100    "cell_type": "code",
 101    "execution_count": 6,
 102    "metadata": {
 103     "collapsed": false
 104    },
 105    "outputs": [
 106     {
 107      "data": {
 108       "text/plain": [
 109        "[1, 0, 0, 0, 1]"
 110       ]
 111      },
 112      "execution_count": 6,
 113      "metadata": {},
 114      "output_type": "execute_result"
 115     }
 116    ],
 117    "source": [
 118     "17.to_digits(2)"
 119    ]
 120   },
 121   {
 122    "cell_type": "code",
 123    "execution_count": 7,
 124    "metadata": {
 125     "collapsed": false
 126    },
 127    "outputs": [
 128     {
 129      "data": {
 130       "text/plain": [
 131        "[0, 1, 3, 5, 7, 9, 33, 99, 313, 585, 717]"
 132       ]
 133      },
 134      "execution_count": 7,
 135      "metadata": {},
 136      "output_type": "execute_result"
 137     }
 138    ],
 139    "source": [
 140     "(0..10**3).select {|i| i.to_s.palindrome? && i.to_s(2).palindrome?}"
 141    ]
 142   },
 143   {
 144    "cell_type": "code",
 145    "execution_count": 8,
 146    "metadata": {
 147     "collapsed": false
 148    },
 149    "outputs": [
 150     {
 151      "data": {
 152       "text/plain": [
 153        "[0, 1, 3, 5, 7, 9, 33, 99, 313, 585, 717, 7447, 9009, 15351, 32223, 39993, 53235, 53835, 73737, 585585]"
 154       ]
 155      },
 156      "execution_count": 8,
 157      "metadata": {},
 158      "output_type": "execute_result"
 159     }
 160    ],
 161    "source": [
 162     "(0..10**6).select {|i| i.to_s.palindrome? && i.to_s(2).palindrome?}"
 163    ]
 164   },
 165   {
 166    "cell_type": "code",
 167    "execution_count": 9,
 168    "metadata": {
 169     "collapsed": false
 170    },
 171    "outputs": [
 172     {
 173      "data": {
 174       "text/plain": [
 175        "872187"
 176       ]
 177      },
 178      "execution_count": 9,
 179      "metadata": {},
 180      "output_type": "execute_result"
 181     }
 182    ],
 183    "source": [
 184     "(0..10**6).select {|i| i.to_s.palindrome? && i.to_s(2).palindrome?}.sum"
 185    ]
 186   },
 187   {
 188    "cell_type": "code",
 189    "execution_count": null,
 190    "metadata": {
 191     "collapsed": true
 192    },
 193    "outputs": [],
 194    "source": []
 195   }
 196  ],
 197  "metadata": {
 198   "kernelspec": {
 199    "display_name": "Ruby 2.4.0",
 200    "language": "ruby",
 201    "name": "ruby"
 202   },
 203   "language_info": {
 204    "file_extension": ".rb",
 205    "mimetype": "application/x-ruby",
 206    "name": "ruby",
 207    "version": "2.4.0"
 208   }
 209  },
 210  "nbformat": 4,
 211  "nbformat_minor": 0
 212 }