16 Longest Valid Parentheses Explained | Stack + Real Dry Run (Interview Proof) | DSA using Java

In this video, I break down the Longest Valid Parentheses problem in Java with a real working solution, clear intuition, and a complete dry run. Most tutorials focus only on code — but I explain why the algorithm works, why we push -1, what “resetting base” really means, and how the stack actually tracks boundaries rather than parentheses. You will learn: ✔ Why we store indices, not characters ✔ Why stack.push(-1) is critical ✔ What “resetting base” actually means ✔ Step-by-step dry run for ")()())" ✔ Edge cases that break naive solutions ✔ Interview-safe mental model If you’re preparing for coding interviews, LeetCode, or DSA exams — this explanation will upgrade your thinking, not just your syntax. 🔹 Full Java code is explained line-by-line in the video. 🔹 No shortcuts, no memorization — real understanding. 📌 Subscribe & follow the playlist to build DSA the right way — from the system level. https://www.youtube.com/playlist?list=PL0n99JuVgkzlaz_g5cM2b5r9lOFD5ghy0 ⏱ Timestamps 00:00 — Problem Statement 00:23 — What “valid parentheses” really means 00:47 — Algorithm 03:14 — Example 07:47 — Full Code Begins 07:52 — longestValidParentheses() Method 08:55 — Case 1: When we see ( 09:33 — Case 2: When we see ) 09:57 — Case 2A: Resetting base explained simply 10:33 — Case 2B: Calculating length 10:54 — main() Method 11:10 - Outro 👍 If this helped you: Like the video Subscribe for DSA explained clearly Comment “STACK” for more problems If this helped you, **LIKE 👍 | SUBSCRIBE 🔔 | SHARE** with your study group!