Search⌘ K
AI Features
Home
Courses
Grokking the Coding Interview Patterns

Solution: Remove Invalid Parentheses

Explore how to use backtracking to remove invalid parentheses from a string while ensuring balanced and valid expressions. Learn to count and remove minimal invalid parentheses and generate all unique valid outputs through recursive exploration of choices.

We'll cover the following...

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≤ ...