Solution: Longest Valid Parentheses
Explore how to identify the longest valid parentheses substring by applying the stack pattern. Learn to track unmatched parentheses with indexes and calculate valid substring lengths efficiently. Understand the time and space complexity of this stack-based solution to prepare 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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