longest_non_repeating_string.py

def longest_non_repeating_string(input_str):
	repeated_chars = {}
	longest_string = ""
	current_string = ""
	for char in input_str:
		if char in repeated_chars:
			current_string = ""
			repeated_chars = {}
		
		current_string += char
		repeated_chars[char] = True

		if len(current_string) > len(longest_string):
			longest_string = current_string
	return longest_string

print longest_non_repeating_string("broadband")
print longest_non_repeating_string("hello abcdefhijkl")
print longest_non_repeating_string("madam am i")
print longest_non_repeating_string("hello worldfair")