euler62.ipynb

   1 {
   2  "cells": [
   3   {
   4    "cell_type": "code",
   5    "execution_count": 1,
   6    "metadata": {},
   7    "outputs": [
   8     {
   9      "data": {
  10       "text/plain": [
  11        "true"
  12       ]
  13      },
  14      "execution_count": 1,
  15      "metadata": {},
  16      "output_type": "execute_result"
  17     }
  18    ],
  19    "source": [
  20     "require_relative 'array-numbers'"
  21    ]
  22   },
  23   {
  24    "cell_type": "code",
  25    "execution_count": 52,
  26    "metadata": {},
  27    "outputs": [
  28     {
  29      "data": {
  30       "text/plain": [
  31        "865"
  32       ]
  33      },
  34      "execution_count": 52,
  35      "metadata": {},
  36      "output_type": "execute_result"
  37     }
  38    ],
  39    "source": [
  40     "cubes = Hash.new {|h, k| h[k] = []}\n",
  41     "cube_roots = {}\n",
  42     "(100..1000).each do |i|\n",
  43     "  c = (i ** 3)\n",
  44     "  p = c.to_digits.sort.join\n",
  45     "  # cubes[p] = (cubes[p] + [c])\n",
  46     "  cubes[p] << c\n",
  47     "  cube_roots[c] = i\n",
  48     "end\n",
  49     "cubes.length"
  50    ]
  51   },
  52   {
  53    "cell_type": "code",
  54    "execution_count": 53,
  55    "metadata": {},
  56    "outputs": [
  57     {
  58      "data": {
  59       "text/plain": [
  60        "{\"01234566\"=>[41063625, 56623104, 66430125]}"
  61       ]
  62      },
  63      "execution_count": 53,
  64      "metadata": {},
  65      "output_type": "execute_result"
  66     }
  67    ],
  68    "source": [
  69     "cubes.select {|k, v| v.length >= 3}"
  70    ]
  71   },
  72   {
  73    "cell_type": "code",
  74    "execution_count": 42,
  75    "metadata": {},
  76    "outputs": [
  77     {
  78      "data": {
  79       "text/plain": [
  80        "345"
  81       ]
  82      },
  83      "execution_count": 42,
  84      "metadata": {},
  85      "output_type": "execute_result"
  86     }
  87    ],
  88    "source": [
  89     "cube_roots[41063625]"
  90    ]
  91   },
  92   {
  93    "cell_type": "code",
  94    "execution_count": 58,
  95    "metadata": {},
  96    "outputs": [
  97     {
  98      "data": {
  99       "text/plain": [
 100        "127035954683"
 101       ]
 102      },
 103      "execution_count": 58,
 104      "metadata": {},
 105      "output_type": "execute_result"
 106     }
 107    ],
 108    "source": [
 109     "target = 5\n",
 110     "\n",
 111     "cubes = Hash.new {|h, k| h[k] = []}\n",
 112     "finished = false\n",
 113     "i = 100\n",
 114     "while ! finished\n",
 115     "  c = (i ** 3)\n",
 116     "  p = c.to_digits.sort.join\n",
 117     "  cubes[p] << c\n",
 118     "  if cubes[p].length == target\n",
 119     "    finished = true\n",
 120     "  else\n",
 121     "    i += 1\n",
 122     "  end\n",
 123     "end\n",
 124     "\n",
 125     "cubes[p].min"
 126    ]
 127   },
 128   {
 129    "cell_type": "code",
 130    "execution_count": null,
 131    "metadata": {
 132     "collapsed": true
 133    },
 134    "outputs": [],
 135    "source": []
 136   }
 137  ],
 138  "metadata": {
 139   "kernelspec": {
 140    "display_name": "Ruby 2.4.0",
 141    "language": "ruby",
 142    "name": "ruby"
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 144   "language_info": {
 145    "file_extension": ".rb",
 146    "mimetype": "application/x-ruby",
 147    "name": "ruby",
 148    "version": "2.4.0"
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 153 }