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

## Python Programming Puzzles: Exercise-87 with Solution

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: [[][][][]]

**Pictorial Presentation:**

**Sample Solution:**

**Python Code:**

```
#License: https://bit.ly/3oLErEI
def test(s):
import re
return re.search(r"\[(\[\])+\]", s).group(0)
brackets = "]][][[]]]"
print("Original List of strings:",brackets)
print("\nFind a valid substring of the said string that contains matching brackets, at least one of which is nested:")
print(test(brackets))
brackets = "]]]]]]]]]]]]]]]]][][][][]]]]]]]]]]][[[][[][[[[[][][][]][[[[[[[[[[[[[[[[[["
print("\nOriginal List of strings:",brackets)
print("\nFind a valid substring of the said string that contains matching brackets, at least one of which is nested:")
print(test(brackets))
```

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: [[][][][]]

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