palindrome.rb

def isPalindrome(word)
  word == word.reverse
end

def isPalindrome2(word)
  i = 0
  lastIndex = word.length - 1
  while i != lastIndex - i
    if word[i] == word[lastIndex - i]
      i += 1
    else
      return false
    end  
  end
  true
end 

def isPalindrome3(word)
  chars = word.split('')
  if chars.size == 1 || chars.size == 2
    chars.first == chars.last 
  elsif chars.first != chars.last
    false
  else  
    chars.shift && chars.pop
    isPalindrome3(chars.join)
  end  
end

puts isPalindrome('abcba')

puts isPalindrome2('abcba')

puts isPalindrome3('abcba')


puts isPalindrome('m')

puts isPalindrome2('m')

puts isPalindrome3('m')


puts isPalindrome('abcd')

puts isPalindrome2('abcd')

puts isPalindrome3('abcd')