# Implement an algorithm to determine if a string has all unique characters.
# What if you can not use additional data structures?

import pytest

def isUnique(input):
  input_len = len(input)
  sub_string = {}
  for i in range(input_len):
    if input[i] in sub_string:
      return False
    else:
      sub_string[input[i]] = True
  return True

def test_unique():
  input1 = 'asdfghjkl'
  input2 = 'aaaawwwwf'
  assert isUnique(input1) == True
  assert isUnique(input2) == False

pytest.main()