I had a pleasure of getting an interview with an upcoming startup (i won’t disclose which one). Besides implementing fizz buzz in ruby, i was asked to write a method that would check for input to be a palindrome.

Palindrome is a word, phrase, number, or other sequence of symbols or elements, whose meaning may be interpreted the same way in either forward or backward.

Keep in mind: using reverse is not allowed 🙂

I wrote two versions since i wasn’t pleased with my first one.

 

Rspec – testing driven development

require 'spec_helper'
require 'blah'

describe "Blah" do 

	it "should match reversed order of the word " do
		palindrome("abba").should == true
		palindrome("abcba").should == true
	end
	it "should reject if reversed order doesnt match" do 
		palindrome("abbac").should_not == true
	end

	it "should handle empty string with passing" do 
		palindrome("").should == true
	end

	it "should handle various cases " do
		palindrome("AbbA").should == true
	end

	it "should handle empty spaces " do
		palindrome("   Ab  bA").should == true
	end
end

 

Version 1

def palindrome2(word)

i = 0
last = -1
word.each_char do |c|
	if word[i] != word[last]
		return false
	end
	i+=1
	last -=1
end

return true

end

 

Version 2

def palindrome(word)
	word = word.downcase.gsub(" ","").chars 
	word.each{|c| return false if  word.shift != word.pop  }
	true
end

I have a feeling there is a better way of writing this.

Thanks