Merge pull request #17 from miguelHx/master

Miguel solution to 1.1 [Python]

Author: fvntr

Python/chapter01/1.1 - Is Unique/miguel_1.1_sol.py

@@ -0,0 +1,80 @@
+"""
+Python version 3.7.0
+1.1
+Implement an algorithm to determine if a string has all unique characters.
+What if you cannot use additional data structures?
+What if the input string is empty?
+I assume that the user will input a non-empty string
+If the string is empty, then raise a ValueError exception
+If the input is NOT a string, then raise a TypeError exception
+"""
+import unittest
+from typing import Callable
+
+
+def is_unique(input_str: str) -> bool:
+    """
+    Determines if input_str has all unique characters.
+    For all characters in the input_str with n >= 1, where n is the number of characters in input_str,
+    there must be no duplicate characters.
+    In the worst case, the run time of this function will be O(n)
+    Space complexity will be O(n)
+    Given:		Expect:
+    tacos		True
+    swag		True
+    bobby		False
+    california	False
+    orbit       True
+    e       True
+    ""      True
+    :param input_str: the string we want to check characters of
+    :return: returns True if input_str has all unique characters, False otherwise
+    """
+    chars_seen = set()
+    for c in input_str:
+        if c in chars_seen:
+            return False
+        chars_seen.add(c)
+    return True
+
+
+def is_unique_no_additional_data_structures(input_str: str) -> bool:
+    """
+    Variant of is_unique.  Uses no additional data structures (besides the variables from the iterator)
+    However, the drawback is that the runtime is O((n*n-1)/2) = O(n^2), where n is the number of characters
+    in the input_str.
+    Given:		Expect:
+    tacos		True
+    swag		True
+    bobby		False
+    california	False
+    orbit       True
+    e       True
+    ""      True
+    :param input_str: the string we want to check characters of
+    :return: returns True if input_str has all unique characters, False otherwise
+    """
+    for i, c in enumerate(input_str):
+        if c in input_str[i+1:]:
+            return False
+    return True
+
+
+class TestIsUniqueFunction(unittest.TestCase):
+    def _run_tests(self, f: Callable[[str], None]) -> None:
+        for case in ["techqueria", "bobby", "california"]:
+            self.assertFalse(f(case), msg=case)
+        for case in ["tacos", "swag", "orbit", "e", ""]:
+            self.assertTrue(f(case), msg=case)
+        with self.assertRaises(TypeError):
+            f(8)
+
+    def test_is_unique(self):
+        self._run_tests(is_unique)
+
+    def test_is_unique_no_additional_data_structures(self):
+        self._run_tests(is_unique_no_additional_data_structures)
+
+
+if __name__ == '__main__':
+    unittest.main()