Python: Find a valid substring of s that contains matching brackets, at least one of which is nested

Last update on March 22 2025 13:47:29 (UTC/GMT +8 hours)

Valid Substring with Nested Brackets

Write a Python program to find a valid substring of a given string that contains matching brackets, at least one of which is nested.

Input: 
 ]][][[]]] 

Output:
[[]]

Input:  
]]]]]]]]]]]]]]]]][][][][]]]]]]]]]]][[[][[][[[[[][][][]][[[[[[[[[[[[[[[[[[ 

Output:
[[][][][]]
 

Visual Presentation:

Sample Solution:

Python Code:

# License: https://bit.ly/3oLErEI

# Define a function named 'test' that takes a string 's' as input
def test(s):
    import re
    # Use regular expression to search for a valid substring with matching brackets
    return re.search(r"\[(\[\])+\]", s).group(0)

# Example 1
brackets1 = "]][][[]]]"
print("Original List of strings:", brackets1)
print("Find a valid substring of the said string that contains matching brackets, at least one of which is nested:")
print(test(brackets1))

# Example 2
brackets2 = "]]]]]]]]]]]]]]]]][][][][]]]]]]]]]]][[[][[][[[[[][][][]][[[[[[[[[[[[[[[[[["
print("\nOriginal List of strings:", brackets2)
print("\nFind a valid substring of the said string that contains matching brackets, at least one of which is nested:")
print(test(brackets2))

Sample Output:

Original List of strings: ]][][[]]]

Find a valid substring of the said string that contains matching brackets, at least one of which is nested:
[[]]

Original List of strings: ]]]]]]]]]]]]]]]]][][][][]]]]]]]]]]][[[][[][[[[[][][][]][[[[[[[[[[[[[[[[[[

Find a valid substring of the said string that contains matching brackets, at least one of which is nested:
[[][][][]]

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python program to extract the shortest valid substring from a string containing nested brackets using a stack.
• Write a Python program to find and return a substring that contains at least one nested pair of matching brackets.
• Write a Python program to use regular expressions to locate a valid substring with nested brackets from an input string.
• Write a Python program to iterate over a string and capture the first occurrence of a substring that features nested parentheses.

Python Code Editor :

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