Ruby/Bsearch is a binary search library for Ruby. It can search the FIRST or LAST occurrence in an array with a condition given by a block.
Tha latest version of Ruby/Bsearch is available at <URL:http://namazu.org/~satoru/ruby-bsearch/> .
Array#bsearch_first (range = Range.new(0, self.length() - 1)) {|x| ...}Return the index of the FIRST occurrence in an array with a condition given by block. Return nil if not found. Optional parameter `range' specifies the range of searching.
Array#bsearch_last (range = Range.new(0, self.length() - 1)) {|x| ...}Return the index of the LAST occurrence in an array with a condition given by block. Return nil if not fount. Optional parameter `range' specifies the range of searching.
Array#bsearch_range (range = Range.new(0, self.length() - 1)) {|x| ...}Return both the FIRST and the LAST occurrence in an array with a condition given by block as Range object. Return nil if not found. Optional parameter `range' specifies the range of searching.
Array#bsearch (range = Range.new(0, self.length() - 1)) {|x| ...}This is an alias to Array#bsearch_first.
% irb --simple-prompt -r 'bsearch.rb'
>> %w(a b c c c d).bsearch_first {|x| x <=> "c"}
=> 2
>> %w(a b c c c d).bsearch {|x| x <=> "c"} # same as above
=> 2
>> %w(a b c c c d).bsearch_last {|x| x <=> "c"}
=> 4
>> %w(a b c c c d).bsearch {|x| x <=> "x"}
=> nil
>> %w(a b c c c d).bsearch_range {|x| x <=> "c"}
=> 2..4
Ruby/Bsearch is a free software with ABSOLUTELY NO WARRANTY under the terms of Ruby's licence.
satoru@namazu.org