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Solution: Remove Invalid Parentheses

Explore how to solve the problem of removing invalid parentheses using a backtracking approach. Learn to identify the minimum number of parentheses to remove and generate all valid expressions by recursion. This lesson helps you implement an algorithm that balances opening and closing parentheses, ensuring unique valid strings as output.

Statement

You are given a string, s, that contains:

  • Lowercase English letters

  • Opening '(' and closing ')' parentheses

A string is considered valid if:

  1. All opening parentheses '(' are closed properly by a matching ')'.

  2. The parentheses are in the correct order and nesting.

  3. 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:

  • 1 ...