Solution: Longest Valid Parentheses
Explore how to identify the longest valid substring of parentheses using the stack pattern. Learn to push and pop indices to track matching pairs and calculate substring lengths efficiently. Understand the underlying algorithm and its O(n) time and space complexity through step-by-step explanation.
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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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