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April 29, 2012 17:11
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Rubyでアルゴリズムやらデータ構造やらのお勉強(Linked List)
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# -*- coding: utf-8 -*- | |
# Cで書かれたアルゴリズムやらデータ構造なりを、自分なりにRubyで表現してみるお勉強PJ。 | |
# 参考書籍(プログラミングの宝箱 アルゴリズムとデータ構造) | |
# Ruby1.9.3で動作確認済み | |
# アイディアだけ聞いて実装イメージの大半を自力でつかめたのはこれと線形探索ぐらいだった気がする。(あってるのか別にして) | |
# でもこれそのものをRubyで使うことはないんだろうな・・・RubyのArrayは可変な上にindex使えるんだし。 | |
$VERBOSE = true | |
class LinkedList | |
class Node | |
attr_accessor :value, :pre, :succ | |
alias_method :next, :succ | |
alias_method :next=, :succ= | |
def initialize(value, pre, succ) | |
@value, @pre, @succ = value, pre, succ | |
end | |
end | |
attr_reader :first, :last | |
def initialize(first_value) | |
@first = @last = Node.new first_value, nil, nil | |
end | |
def <<(value) | |
@last.succ = Node.new value, @last, nil | |
@last = @last.succ | |
self | |
end | |
def each | |
return to_enum(__callee__) unless block_given? | |
node = @first | |
yield node.value | |
while node = node.succ | |
yield node.value | |
end | |
self | |
end | |
def reverse_each | |
return to_enum(__callee__) unless block_given? | |
node = @last | |
yield node.value | |
while node = node.pre | |
yield node.value | |
end | |
self | |
end | |
end | |
# Overview | |
list = LinkedList.new 7 | |
list << 9 << 200 << -3 | |
p list.first.value #=> 7 | |
p list.last.value #=> -3 | |
list.each do |value| | |
p value | |
end | |
#=> 7, 9, 200, -3 | |
list.reverse_each do |value| | |
p value | |
end | |
#=> -3, 200, 9, 7 |
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