Python: Find the minimum window in a given string which will contain all the characters of another given string

Python String: Exercise-74 with Solution

Write a Python program to find the minimum window in a given string which will contain all the characters of another given string.

Example 1
Input
str1 = " PRWSOERIUSFK "
str2 = " OSU "
Output:
Minimum window is "OERIUS"

Sample Solution:

Python Code:

import collections
def min_window(str1, str2):
    result_char, missing_char = collections.Counter(str2), len(str2)
    i = p = q = 0
    for j, c in enumerate(str1, 1):
        missing_char -= result_char[c] > 0
        result_char[c] -= 1
        if not missing_char:
            while i < q and result_char[str1[i]] < 0:
                result_char[str1[i]] += 1
                i += 1
            if not q or j - i <= q - p:
                p, q = i, j
    return str1[p:q]
           
str1 = "PRWSOERIUSFK"
str2 = "OSU"
print("Original Strings:\n",str1,"\n",str2)
print("Minimum window:")
print(min_window(str1,str2))

Sample Output:

Original Strings:
 PRWSOERIUSFK 
 OSU
Minimum window:
OERIUS

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