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Solution: Remove Invalid Parentheses

Explore a backtracking approach to remove invalid parentheses from a string while maintaining valid balancing. Learn to identify minimum removals and generate all balanced expressions through recursive decisions. This lesson helps you understand the process of pruning invalid options and creating unique valid string combinations using algorithmic problem-solving techniques.

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 ...