Problem Link - Flatten String in Recursion
Problem Statement:
You are given a string that may contain nested parentheses, each with inner strings. The goal is to write a recursive function, flatten_string, that flattens the given string by removing all parentheses and concatenating the characters in the nested structure.
Approach:
1. Character by Character Traversal:
- We traverse the string one character at a time.
- For each character, we check whether it’s an opening parenthesis
(
, closing parenthesis)
, or just a regular letter.
2. Handling Parentheses:
- Opening Parenthesis
(
:- When we find
(
, it means we’re entering a nested section. - We then recursively call our function to handle everything inside this new section, until we hit the closing parenthesis
)
. - The result from the nested section is appended to our main result.
- When we find
- Closing Parenthesis
)
:- When we find
)
, it means we’re done with this section, so we stop the current recursive call and return the result we’ve collected so far.
- When we find
3. Regular Characters: Any letter that’s not inside parentheses is added directly to our result string.
4. Edge Case: If there are no parentheses, the function will just go through the string and return it unchanged.
Complexity:
- Time Complexity:
O(n)
wheren
is the length of the string. Each character is processed exactly once. - Space Complexity:
O(n)
due to the recursion stack, especially for deeply nested parentheses.