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Solution: Remove Invalid Parentheses

Explore how to solve the problem of removing invalid parentheses from a string by using a backtracking algorithm. Learn to count and remove the minimum number of unmatched parentheses and generate all unique valid combinations. Understand the recursive process balancing open and close parentheses, ensuring valid expressions.

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 ...