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Python – Possible Substring count from String

  • Last Updated : 09 Jul, 2021

Given target string and argument substring, count how many substrings can be constructed using string characters, repetitions not allowed.

Input : test_str = “geksefokesgergeeks”, arg_str = “geeks” 
Output : 3 
Explanation : “geeks” can be created 3 times using string characters.

Input : test_str = “gefroksefokesgergeeks”, arg_str = “for” 
Output : 2 
Explanation : “for” can be created 2 times using string characters. 
 

Method #1 : Using count() + min() + set()

The combination of above functions can be used to solve this problem. In this, we divide the count of each element of arg string with count of target string character, and using min(), the lowest element is returned. The logic behind is that any element above min would mean the minimum element would miss from that string onwards.



Python3




# Python3 code to demonstrate working of
# Possible Substring count from String
# Using min() + list comprehension + count()
 
# initializing string
test_str = "gekseforgeeks"
 
# printing original string
print("The original string is : " + str(test_str))
 
# initializing arg string
arg_str = "geeks"
 
# using min and count to get minimum possible
# occurrence of character
res = min(test_str.count(char) // arg_str.count(char) for char in set(arg_str))
 
# printing result
print("Possible substrings count : " + str(res))
Output
The original string is : gekseforgeeks
Possible substrings count : 2

Method #2 : Using Counter() + list comprehension

This is yet another way in which this task can be performed. In this, we perform the task of counting using Counter() and list comprehension is used to bind the result together, using min() performing similar task as previous method.

Python3




# Python3 code to demonstrate working of
# Possible Substring count from String
# Using Counter() + list comprehension
from collections import Counter
 
# initializing string
test_str = "gekseforgeeks"
 
# printing original string
print("The original string is : " + str(test_str))
 
# initializing arg string
arg_str = "geeks"
 
# using Counter to get character frequencies
temp1 = Counter(test_str)
temp2 = Counter(arg_str)
res = min(temp1[char] // temp2[char] for char in temp2.keys())
 
# printing result
print("Possible substrings count : " + str(res))
Output
The original string is : gekseforgeeks
Possible substrings count : 2

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