June 22, 2018

Check if a string has all unique characters python

By Mohammed Abualrob Algorithms and Data Structures, Code Snippets, Interview Questions 0 Comments

Problem

Given a string of characters. Implement an algorithm in Python to check if the string has all unique characters.

Solution

One solution is to get the unique characters in the string using a set. If the length of the input string is the same as the length of the set then the string has all unique characters. Another solution is to insert string characters into a dictionary. If there is at least one character with count greater than one then the input string does not have all unique characters.

Code

Here is the implementation in Python…

# Import python unit tests module
import unittest  

# This function converts the input string to a set then
# compares the length of the set with the length of the
# input string. If the length is the same then the
# string has all unique characters
def allUniqueSet(mystr):
	return len(mystr) == len(set(mystr))

# This function uses the characters in the input string
# as keys in a dictionary. The value associated with
# a key is the count of that character in the string
# If all keys have a count of one then all characters
# are unique otherwise at least one character is repeated
def allUniqueDic(mystr):
	dic = {}
	for c in mystr:
	   dic[c] = 0

	for c in mystr:
	   dic[c]+= 1

	for c, count in dic.items():
	   if count > 1:
	      return False
	return True

# This class uses python unit tests to test our code
class Tests(unittest.TestCase):    

	def test_case_01(self):
		self.assertTrue(allUniqueSet("isco"))

	def test_case_02(self):                           
	  self.assertFalse(allUniqueSet("cisco"))  

	def test_case_03(self):                           
	  self.assertTrue(allUniqueDic("isco"))

	def test_case_04(self):                           
	  self.assertFalse(allUniqueDic("cisco"))  
 
# Run test suite
unittest.main()

# Import python unit tests module

import unittest

# This function converts the input string to a set then

# compares the length of the set with the length of the

# input string. If the length is the same then the

# string has all unique characters

def allUniqueSet(mystr):

return len(mystr) == len(set(mystr))

# This function uses the characters in the input string

# as keys in a dictionary. The value associated with

# a key is the count of that character in the string

# If all keys have a count of one then all characters

# are unique otherwise at least one character is repeated

def allUniqueDic(mystr):

dic = {}

for c in mystr:

dic[c] = 0

for c in mystr:

dic[c]+= 1

for c, count in dic.items():

if count > 1:

return False

return True

# This class uses python unit tests to test our code

class Tests(unittest.TestCase):

def test_case_01(self):

self.assertTrue(allUniqueSet("isco"))

def test_case_02(self):

self.assertFalse(allUniqueSet("cisco"))

def test_case_03(self):

self.assertTrue(allUniqueDic("isco"))

def test_case_04(self):

self.assertFalse(allUniqueDic("cisco"))

# Run test suite

unittest.main()

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Check if a string has all unique characters python

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