Solution: Longest Valid Parentheses
Explore how to identify the longest valid parentheses substring in a string using a stack. Understand the algorithm that leverages stack operations and index management to solve this classic coding interview problem efficiently. This lesson helps you implement and analyze the time and space complexity of the stack-based approach, building skills essential for coding interviews.
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Statement
You are given a string composed entirely of ‘(’ and ‘)’ characters. Your goal is to identify the longest contiguous segment (substring) within this string that represents a “well-formed” or “valid” sequence of parentheses.
A substring is considered valid if:
Every opening parenthesis ‘
(’ has a corresponding closing parenthesis ‘)’.The pairs of parentheses are correctly nested.
Return the length of this longest valid substring.
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