First non repeating character position in a string
# First non repeating character position in a string
def first_non_repeating_letter(str)
    strL = str.downcase
    strL.each_char.with_index do |v, i|
        if strL.index(v) == strL.rindex(v)
            return i
        end
    end
    -1
end
print "First non repeating character position = ", 
	first_non_repeating_letter("abcdcba");  # 3
