開発環境
- OS X Lion - Apple(OS)
- BBEdit - Bare Bones Software, Inc.(Text Editor)
- Script言語:Ruby
『初めてのプログラミング 第2版』(Chris Pine 著、長尾 高弘 訳、オライリー・ジャパン、2010年、ISBN978-4-87311-469-9)の 10章(章全部で復習), 10.3(練習問題)シャッフル(再帰) を解いてみる。
その他参考書籍
- 『プログラミング言語 Ruby』David Flanagan, まつもと ゆきひろ 著 、卜部 昌平 監訳、長尾 高弘 訳、オライリー・ジャパン、2009年、ISBN978-4-87311-394-4)
- Rubyクックブック ―エキスパートのための応用レシピ集
シャッフル(再帰)
コード(BBEdit)
sample.rb
#!/usr/bin/env ruby1.9
#-*- coding: utf-8 -*-
def shuffle some_array
recursive_shuffle some_array, []
end
def recursive_shuffle some_array, shuffled_array
return shuffled_array if some_array.length == 0
a = some_array[0, some_array.length]
i = rand (a.length - 1)
shuffled_array.push a.slice!(i)
recursive_shuffle a, shuffled_array
end
a = [1, 2, 3, 4, 5, 'A','B','C','D','E', 'a','b','c','d','e']
shuffled_a = shuffle a
puts "シャッフル前: #{a}"
puts "シャッフル後: #{shuffled_a}"
入出力結果(Terminal)
$ ./sample.rb シャッフル前: [1, 2, 3, 4, 5, "A", "B", "C", "D", "E", "a", "b", "c", "d", "e"] シャッフル後: ["a", "b", 3, "D", "B", 4, "C", 5, "c", "A", 2, "E", 1, "d", "e"] $ ./sample.rb シャッフル前: [1, 2, 3, 4, 5, "A", "B", "C", "D", "E", "a", "b", "c", "d", "e"] シャッフル後: ["D", 5, 4, "A", "C", "c", "E", "d", "b", 2, 3, "B", "a", 1, "e"] $ ./sample.rb シャッフル前: [1, 2, 3, 4, 5, "A", "B", "C", "D", "E", "a", "b", "c", "d", "e"] シャッフル後: ["C", 5, "a", "c", "D", "b", "d", "E", "B", 3, 2, 1, "A", 4, "e"] $ ./sample.rb シャッフル前: [1, 2, 3, 4, 5, "A", "B", "C", "D", "E", "a", "b", "c", "d", "e"] シャッフル後: ["D", 1, "b", "B", "A", "a", 4, 2, 5, "E", "C", 3, "d", "c", "e"] $ ./sample.rb シャッフル前: [1, 2, 3, 4, 5, "A", "B", "C", "D", "E", "a", "b", "c", "d", "e"] シャッフル後: ["a", 3, "C", "D", 4, 5, "A", "E", "b", 1, "B", 2, "c", "d", "e"] $
ちなみにJavaScriptの場合。
コード(BBEdit)
function shuffle(a) {
return recursive_shuffle(a, []);
}
function recursive_shuffle( some_array, shuffled_array ) {
if ( some_array.length == 0 ) {
return shuffled_array;
}
var a = some_array.slice(),
i = Math.floor(Math.random() * a.length);
shuffled_array.push( a.splice(i, 1)[0] );
return recursive_shuffle( a, shuffled_array);
}
var a = [1, 2, 3, 4, 5, 'A','B','C','D','E', 'a','b','c','d','e']
var shuffled_a = shuffle(a);
var result = "シャッフル前: " + a + "\n" +
"シャッフル後: " + shuffled_a + "\n";
$('#pre0').text(result);
pythonの場合。
sample.py
コード(BBEdit)
#!/usr/bin/env python3.3
#-*- coding: utf-8 -*-
import random
def recursive_shuffle( some_l, shuffled_l):
if len(some_l) == 0: return shuffled_l
l = some_l[:]
i = random.randint(0, len(l) - 1)
shuffled_l.append(l.pop(i))
return recursive_shuffle(l, shuffled_l)
def shuffle(l):
return recursive_shuffle(l, [])
l = [1, 2, 3, 4, 5, 'A','B','C','D','E', 'a','b','c','d','e']
shuffled_l = shuffle( l )
print("ソート前: {0}".format( l ))
print("ソート後: {0}".format(shuffled_l))
入出力結果(Terminal)
$ ./sample.py ソート前: [1, 2, 3, 4, 5, 'A', 'B', 'C', 'D', 'E', 'a', 'b', 'c', 'd', 'e'] ソート後: ['c', 'a', 1, 4, 5, 'b', 'e', 2, 'C', 3, 'B', 'E', 'A', 'D', 'd'] $ ./sample.py ソート前: [1, 2, 3, 4, 5, 'A', 'B', 'C', 'D', 'E', 'a', 'b', 'c', 'd', 'e'] ソート後: [3, 'e', 4, 'D', 'b', 1, 'd', 'a', 'C', 'B', 'A', 5, 2, 'c', 'E'] $ ./sample.py ソート前: [1, 2, 3, 4, 5, 'A', 'B', 'C', 'D', 'E', 'a', 'b', 'c', 'd', 'e'] ソート後: [2, 'E', 4, 'b', 'D', 'B', 3, 'A', 'a', 'c', 'e', 'd', 'C', 1, 5] $ ./sample.py ソート前: [1, 2, 3, 4, 5, 'A', 'B', 'C', 'D', 'E', 'a', 'b', 'c', 'd', 'e'] ソート後: ['d', 'E', 'A', 'D', 'B', 3, 'e', 1, 4, 'C', 5, 'a', 2, 'b', 'c'] $ ./sample.py ソート前: [1, 2, 3, 4, 5, 'A', 'B', 'C', 'D', 'E', 'a', 'b', 'c', 'd', 'e'] ソート後: ['e', 2, 'D', 'A', 3, 4, 'B', 'd', 5, 'a', 'b', 'C', 'E', 1, 'c'] $
perlの場合。
sample.pl
コード(BBEdit)
#!/usr/bin/env perl
use strict;
use warnings;
use utf8;
use 5.016;
binmode STDIN, ":utf8";
binmode STDOUT, ":utf8";
sub shuffle {
my $l = shift;
recursive_shuffle($l, []);
}
sub recursive_shuffle {
my($some_l, $shuffled_l) = @_;
return $shuffled_l unless @$some_l;
my @l = @$some_l;
my $i = rand @l;
push @$shuffled_l, splice(@l, $i, 1);
recursive_shuffle(\@l, $shuffled_l);
}
my @l = (1, 2, 3, 4, 5, 'A','B','C','D','E', 'a','b','c','d','e');
my $shuffled_l = shuffle \@l;
print "ソート前: @l\n";
print "ソート後: @$shuffled_l\n";
入出力結果(Terminal)
$ ./sample.pl ソート前: 1 2 3 4 5 A B C D E a b c d e ソート後: 1 C b 3 B 5 2 a 4 c E D e A d $ ./sample.pl ソート前: 1 2 3 4 5 A B C D E a b c d e ソート後: 1 B d b a C 3 E 5 2 e A 4 D c $ ./sample.pl ソート前: 1 2 3 4 5 A B C D E a b c d e ソート後: 2 B C a 5 A b 3 4 c D e d 1 E $ ./sample.pl ソート前: 1 2 3 4 5 A B C D E a b c d e ソート後: E c a 1 D e b A 3 B 5 2 4 d C $ ./sample.pl ソート前: 1 2 3 4 5 A B C D E a b c d e ソート後: B A D C 4 5 d b c E a 3 2 1 e $ ./sample.pl ソート前: 1 2 3 4 5 A B C D E a b c d e ソート後: 2 c E D 5 C a 4 1 A e 3 B b d $
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