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# Python – Number of positions where Substrings Match of Length K

• Last Updated : 02 Sep, 2020

Given 2 Strings, count positions where substrings of Length K Match.

Input : test_str1 = ‘geeksforgeeks’, test_str2 = ‘peeksformeeks’, K = 4
Output : 4
Explanation : 4 positions match K length Substings.

Input : test_str1 = ‘geeksforgeeks’, test_str2 = ‘peeksformeeks’, K = 5
Output : 3
Explanation : 3 positions match K length Substings.

Method #1 : Using list comprehension + min() + slicing

In this, we iterate through strings till length of minimum string, and the comparison is done by slicing using string slicing. Iteration is done through loop inside list comprehension.

## Python3

 # Python3 code to demonstrate working of # Number of positions where Substrings Match of Length K# Using list comprehension + min() + slicing  # initializing stringstest_str1 = 'geeksforgeeks'test_str2 = 'peeksformeeks'  # printing original stringsprint("The original string 1 is : " + str(test_str1))print("The original string 2 is : " + str(test_str2))  # initializing K K = 3   # checking for substrings, # using len() to get total countres = len([test_str1[idx : idx + K] for idx in range(min(len(test_str1), len(test_str2)) - K - 1)        if test_str1[idx : idx + K] == test_str2[idx : idx + K]])  # printing result print("Number of positions of matching K length Substrings : " + str(res))
Output
The original string 1 is : geeksforgeeks
The original string 2 is : peeksformeeks
Number of positions of matching K length Substrings : 5

Method #2 : Using map() + list comprehension

In this, we extract all K length substrings of one string and then using in operator and map, check for each substring if present in other String, this ignores the positional factor of problem.

## Python3

 # Python3 code to demonstrate working of # Number of positions where Substrings Match of Length K# Using map() + list comprehension  # initializing stringstest_str1 = 'geeksforgeeks'test_str2 = 'peeksformeeks'  # printing original stringsprint("The original string 1 is : " + str(test_str1))print("The original string 2 is : " + str(test_str2))  # initializing K K = 3   # Extracting Substringssubs_str = [test_str1[idx : idx + K] for idx in range(len(test_str1) - K - 1)]  # checking in other string# using count() to get numberres = list(map(lambda ele: ele in test_str2, subs_str)).count(True)  # printing result print("Number of positions of matching K length Substrings : " + str(res))
Output
The original string 1 is : geeksforgeeks
The original string 2 is : peeksformeeks
Number of positions of matching K length Substrings : 5

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