Solution: Remove Invalid Parentheses
Explore the backtracking approach to remove invalid parentheses from a string by generating all valid expressions that minimize removals. Understand how to count unmatched parentheses and recursively build balanced strings, ensuring all unique valid results are returned.
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Statement
You are given a string, s, that contains:
Lowercase English letters
Opening
'('and closing')'parentheses
A string is considered valid if:
All opening parentheses
'('are closed properly by a matching')'.The parentheses are in the correct order and nesting.
Letters can appear anywhere and do not affect validity.
Return all possible valid strings that can be formed by removing the minimum number of invalid parentheses. The answer must be a list of unique strings, in any order.
Constraints:
s.lengthsconsists of lowercase English letters and parentheses'('and')'.There will be at most
20parentheses ins. ...