Day 79: Python Program to Find Common Characters in Two Strings

 from collections import Counter

def find_non_common_letters(str1, str2):

    count1 = Counter(str1)

    count2 = Counter(str2)

    non_common_letters = (count1 - count2) + (count2 - count1)

    result = []

    for char, count in non_common_letters.items():

        result.extend([char] * count)  

    return result

str1 = input("Enter the first string: ")

str2 = input("Enter the second string: ")

non_common_letters = find_non_common_letters(str1, str2)

print("Letters that are not common in both strings:", non_common_letters)

#source code --> clcoding.com 

Code Explanation:

Importing Counter:

from collections import Counter: This imports the Counter class from Python’s collections module. A Counter is a special dictionary that counts the occurrences of elements in an iterable, such as a string.

Function find_non_common_letters:

def find_non_common_letters(str1, str2): This defines a function that takes two strings, str1 and str2, as input and returns a list of letters that are not common between the two strings.

Counting Characters:

count1 = Counter(str1): This creates a Counter object for str1, which counts how many times each character appears in the string str1.

For example, for str1 = "aab", count1 would be: {'a': 2, 'b': 1}.

count2 = Counter(str2): Similarly, this creates a Counter object for str2, counting character occurrences in str2.

Finding Non-Common Letters:

non_common_letters = (count1 - count2) + (count2 - count1):

count1 - count2: This finds the letters that appear in str1 but not in str2, keeping the count of occurrences.

count2 - count1: This finds the letters that appear in str2 but not in str1, again keeping the count of occurrences.

The + operator combines these two parts, effectively getting the total set of non-common letters with their counts.

Building the Result List:

result = []: Initializes an empty list, result, to store the non-common letters.

for char, count in non_common_letters.items(): This loops through each character (char) and its count (count) from non_common_letters.

result.extend([char] * count): This line adds the character char to the list result multiple times (according to its count). For example, if 'a': 3, the character 'a' will appear 3 times in result.

Returning the Result:

return result: This returns the final list result, which contains all the letters that are not common between str1 and str2, each appearing the appropriate number of times.

Taking User Input:

str1 = input("Enter the first string: "): Takes the first string input from the user.

str2 = input("Enter the second string: "): Takes the second string input from the user.

Calling the Function:

non_common_letters = find_non_common_letters(str1, str2): This calls the find_non_common_letters function with the two user-provided strings and stores the result in non_common_letters.

Printing the Result:

print("Letters that are not common in both strings:", non_common_letters): This prints the list of non-common letters.