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Solution: Remove Invalid Parentheses

Explore how to apply backtracking to remove the minimum number of invalid parentheses from a string and generate all valid expressions. Understand the process of counting mismatched parentheses, making recursive choices, and ensuring balanced outcomes. This lesson helps you implement an algorithm to solve parentheses validation challenges efficiently.

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 ...