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Solution to Project Euler problem 62

db4
Guillaume Nargeot 2009-10-26 21:17:06 +09:00
parent f1a10d2d7f
commit 0a350bbe6e
4 changed files with 69 additions and 10 deletions
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extra/project-euler/062/062-tests.factor Normal file
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USING: project-euler.062 tools.test ;
IN: project-euler.062.tests
[ 127035954683 ] [ euler062 ] unit-test

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extra/project-euler/062/062.factor Normal file
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! Copyright (c) 2009 Guillaume Nargeot.
! See http://factorcode.org/license.txt for BSD license.
USING: arrays assocs hashtables kernel math math.functions
project-euler.common sequences sorting ;
IN: project-euler.062
! http://projecteuler.net/index.php?section=problems&id=062
! DESCRIPTION
! -----------
! The cube, 41063625 (345^3), can be permuted to produce two
! other cubes: 56623104 (384^3) and 66430125 (405^3). In
! fact, 41063625 is the smallest cube which has exactly three
! permutations of its digits which are also cube.
! Find the smallest cube for which exactly five permutations of
! its digits are cube.
! SOLUTION
! --------
<PRIVATE
: cube ( n -- n^3 ) 3 ^ ; inline
: >key ( n -- k ) cube number>digits natural-sort ; inline
: has-entry? ( n assoc -- ? ) [ >key ] dip key? ; inline
: (euler062) ( n assoc -- n )
2dup has-entry? [
2dup [ >key ] dip
[ dup 0 swap [ 1 + ] change-nth ] change-at
2dup [ >key ] dip at first 5 =
[
[ >key ] dip at second
] [
[ 1 + ] dip (euler062)
] if
] [
2dup 1 pick cube 2array -rot
[ >key ] dip set-at [ 1 + ] dip
(euler062)
] if ;
PRIVATE>
: euler062 ( -- answer )
1 1 <hashtable> (euler062) ;
! [ euler062 ] 100 ave-time
! 78 ms ave run time - 0.9 SD (100 trials)
SOLUTION: euler062

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extra/project-euler/062/authors.txt Normal file
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Guillaume Nargeot

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extra/project-euler/project-euler.factor
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project-euler.045 project-euler.046 project-euler.047 project-euler.048
project-euler.049 project-euler.051 project-euler.052 project-euler.053
project-euler.054 project-euler.055 project-euler.056 project-euler.057
project-euler.058 project-euler.059 project-euler.063 project-euler.065
project-euler.067 project-euler.069 project-euler.071 project-euler.072
project-euler.073 project-euler.074 project-euler.075 project-euler.076
project-euler.079 project-euler.081 project-euler.085 project-euler.092
project-euler.097 project-euler.099 project-euler.100 project-euler.102
project-euler.112 project-euler.116 project-euler.117 project-euler.124
project-euler.134 project-euler.148 project-euler.150 project-euler.151
project-euler.164 project-euler.169 project-euler.173 project-euler.175
project-euler.186 project-euler.188 project-euler.190 project-euler.203
project-euler.215 ;
project-euler.058 project-euler.059 project-euler.062 project-euler.063
project-euler.065 project-euler.067 project-euler.069 project-euler.071
project-euler.072 project-euler.073 project-euler.074 project-euler.075
project-euler.076 project-euler.079 project-euler.081 project-euler.085
project-euler.092 project-euler.097 project-euler.099 project-euler.100
project-euler.102 project-euler.112 project-euler.116 project-euler.117
project-euler.124 project-euler.134 project-euler.148 project-euler.150
project-euler.151 project-euler.164 project-euler.169 project-euler.173
project-euler.175 project-euler.186 project-euler.188 project-euler.190
project-euler.203 project-euler.215 ;
IN: project-euler
<PRIVATE