Reversing Strings in Java with Efficient String Traversal

Most people overcomplicate this problem. At first glance, it feels like we need extra space or another array… But the trick is simple: Since the array is sorted, duplicates are always next to each other. Once you notice that, you can solve it in-place using a Two Pointer approach — no extra space needed. Small observation → big optimization. If you’re preparing for coding interviews, this pattern shows up more often than you think. Have you used this approach before? #DSA #TwoPointers #Java #CodingInterview #ProblemSolving #LeetCode #SoftwareEngineering

🚀 Started something I've been meaning to do for a while — a dedicated 𝗚𝗶𝘁𝗛𝘂𝗯 𝗿𝗲𝗽𝗼 𝗳𝗼𝗿 𝗟𝗟𝗗 (𝗟𝗼𝘄 𝗟𝗲𝘃𝗲𝗹 𝗗𝗲𝘀𝗶𝗴𝗻) interview prep in Java! 📌 𝗵𝘁𝘁𝗽𝘀://𝗴𝗶𝘁𝗵𝘂𝗯.𝗰𝗼𝗺/𝗱𝗮𝗿𝘀𝗵𝗲𝗲𝗹-𝗿𝗮𝘁𝗵𝗼𝗿𝗲/𝗹𝗹𝗱-𝗷𝗮𝘃𝗮-𝗽𝗿𝗮𝗰𝘁𝗶𝗰𝗲 The goal? 50 LLD projects, all in one place — designed the way interviewers actually expect them. Starting from the classics like: ✅ Tic-Tac-Toe (done — with Strategy pattern, undo & bot support) ⏳ Snake & Ladder, Parking Lot, Vending Machine... And going all the way up to real-world system designs: 🔧 API Throttling System 📞 Truecaller 💼 LinkedIn-style features ...and 40+ more. Every project follows: → SOLID principles → Strategy & Builder patterns → Clean package structure (models, strategies, exceptions) → Interview-style driver code — no Scanner, just real scenarios If you're prepping for LLD rounds, this could save you hours of scattered searching. ⭐ 𝗦𝘁𝗮𝗿 or 🍴 𝗙𝗼𝗿𝗸 𝗶𝘁 — all 50 projects will land here as I build them out weekly. Would love feedback from folks who've cracked LLD rounds — what problems did you face that I should cover? Drop them in the comments! 👇 #Java #LLD #SystemDesign #InterviewPrep #DesignPatterns #OpenSource

Backend Interview Prep in 2026 👇 Most people: ❌ Watch random videos ❌ Read scattered blogs ❌ Forget everything in 2 days Smart people: ✅ Follow structured learning ✅ Practice real scenarios ✅ Focus on system design That’s exactly why I created this 👇 📘 Backend Interview Master PDF 👉 Link: https://lnkd.in/gbF6u9ni 🎁 Use JAVA25 for 15% OFF. Don’t prepare hard. Prepare smart. #Java #Backend #SystemDesign

🚀 Spring Boot Interview Concept: @PathVariable vs @RequestParam vs @RequestBody Understanding when to use each annotation is very important for designing clean REST APIs 👇 🔹 @PathVariable 👉 Used to identify a specific resource 📌 Example: /users/10 → Fetch user with ID = 10 🔹 @RequestParam 👉 Used for filtering, searching, or optional inputs 📌 Example: /users?role=admin&active=true 🔹 @RequestBody 👉 Used to send complete object data (mostly in POST/PUT APIs) 📌 Example (JSON): { "name": "Ankit", "age": 25 } One-Line Rule to Remember: @PathVariable → resource identify @RequestParam → filter/search @RequestBody → send full object #Java #SpringBoot #BackendDevelopment #RESTAPI #InterviewPreparation #SoftwareEngineering

Here is one the most asked technical interview questions, LeetCode: Longest Substring Without Repeating Characters (medium) Given a string, find the length of the longest substring without repeating characters. 💡 Key idea: Use a sliding window and adjust it whenever a duplicate appears. 🧠 Solution: - Use two pointers to form a window and a hashmap to track character positions. - Move the right pointer through the string. - If a character repeats inside the window, move the left pointer past its last position. - Update the max length at each step. Time Complexity and Space Complexity: O(n) #LeetCode #Algorithms #CodingInterview #SoftwareEngineering #DSA #Java

Most people solve “Valid Palindrome” like this. Clean the string → reverse → compare. It works… but that’s not what interviewers are looking for. The real test is: 👉 Can you handle messy input? 👉 Can you avoid extra space? 👉 Can you think in constraints? That’s where Two Pointers comes in. Small problem. Big difference in thinking. #DSA #Java #CodingInterview #TwoPointers #ProblemSolving #SoftwareEngineering #TechLearning

Spring Boot Interview Series — Post 8 Spring fails when it finds two beans of the same type and doesn't know which to inject. NoUniqueBeanDefinitionException: expected single matching bean but found 2: upiPaymentService, cardPaymentService Two ways to fix this. @Primary - tells Spring to use that bean by default when multiple candidates of the same type exist. @Qualifier - resolves ambiguity when multiple beans of the same type exist. You specify exactly which bean to inject by name. When using constructor injection - which is the recommended approach - @Qualifier goes on the constructor parameter, not the field. Used together - @Primary sets the app-wide default. @Qualifier overrides it at specific injection points. If Spring can't decide which bean to inject, you have two choices - tell it what the default is, or tell it exactly what you want. #SpringBoot #Java #JavaDeveloper #BackendDevelopment #SpringFramework

🚀 A small #learning from my recent interview In one of my recent interviews, I was asked to write a program to create a deadlock and then explain how to fix it. Honestly, I’ve read about deadlocks before, but writing it during an interview made me think more practically. 𝐓𝐰𝐨 𝐭𝐡𝐫𝐞𝐚𝐝𝐬, 𝐭𝐰𝐨 𝐫𝐞𝐬𝐨𝐮𝐫𝐜𝐞𝐬: Thread 1 locks one resource and waits for the other Thread 2 does the opposite And that’s it… both threads are 𝐬𝐭𝐮𝐜𝐤 𝐟𝐨𝐫𝐞𝐯𝐞𝐫 What I liked about this question is — it’s simple, but it checks how well we understand real-world thread behavior. The discussion didn’t stop at just creating the deadlock. The interviewer was more interested in how I would avoid it. 𝐒𝐨𝐦𝐞 𝐤𝐞𝐲 𝐭𝐚𝐤𝐞𝐚𝐰𝐚𝐲𝐬 𝐟𝐨𝐫 𝐦𝐞: --> Always follow a consistent order while acquiring locks --> Be careful with nested synchronization --> Think about alternatives like tryLock or timeouts It was a good reminder that multithreading is not just about writing code, but about writing safe and predictable code. #Java #Multithreading #Concurrency #JavaDeveloper #BackendDevelopment #SoftwareEngineering #InterviewExperience #TechInterview #CodingInterview #Learning

𝐉𝐚𝐯𝐚 𝐌𝐮𝐥𝐭𝐢𝐭𝐡𝐫𝐞𝐚𝐝𝐢𝐧𝐠 — 𝐌𝐨𝐬𝐭 𝐃𝐞𝐯𝐞𝐥𝐨𝐩𝐞𝐫𝐬 𝐋𝐞𝐚𝐫𝐧 𝐈𝐭… 𝐁𝐮𝐭 𝐅𝐞𝐰 𝐓𝐫𝐮𝐥𝐲 𝐔𝐧𝐝𝐞𝐫𝐬𝐭𝐚𝐧𝐝 𝐈𝐭. I’ve seen many developers struggle with multithreading in interviews — not because it’s too hard, but because they only learn it theoretically. So I created this simple visual cheat sheet 👇 Here’s what you should ACTUALLY focus on: 🔹 Thread Basics Creating threads is easy: Runnable Callable But knowing when to use which is what matters. 🔹 Thread Lifecycle New → Runnable → Running → Waiting → Terminated 👉 Interviewers LOVE asking this flow with real scenarios. 🔹 Synchronization This is where things get tricky: Race conditions Deadlocks Data inconsistency ✔ Use synchronized / Lock carefully ✔ Keep critical sections minimal 🔹 Executor Framework (Most Important) Stop creating threads manually ❌ Use: ✔ ExecutorService ✔ Thread pools ✔ Future / Callable 👉 This is what real production systems use. 🔹 Inter-thread Communication wait(), notify(), notifyAll() 👉 Not just theory — understand when threads should wait and wake up 🔹 Concurrent Collections ConcurrentHashMap CopyOnWriteArrayList 👉 Essential for multi-threaded applications 🔹 Common Problems ⚠ Deadlock ⚠ Starvation ⚠ Thread leaks 👉 If you can explain EVEN ONE real issue → you stand out in interviews. 💡 Reality: Multithreading is not about writing code… It’s about writing safe + scalable + production-ready code 𝐈𝐟 𝐲𝐨𝐮’𝐫𝐞 𝐬𝐭𝐫𝐮𝐠𝐠𝐥𝐢𝐧𝐠 𝐭𝐨 𝐜𝐫𝐚𝐜𝐤 𝐉𝐚𝐯𝐚 𝐢𝐧𝐭𝐞𝐫𝐯𝐢𝐞𝐰𝐬 (𝟐–𝟔 𝐲𝐞𝐚𝐫𝐬 𝐞𝐱𝐩𝐞𝐫𝐢𝐞𝐧𝐜𝐞), 𝐃𝐌 𝐦𝐞 𝐩𝐞𝐫𝐬𝐨𝐧𝐚𝐥𝐥𝐲 — 𝐈’𝐥𝐥 𝐠𝐮𝐢𝐝𝐞 𝐲𝐨𝐮 𝐨𝐧𝐞-𝐭𝐨-𝐨𝐧𝐞 𝐰𝐢𝐭𝐡 𝐭𝐡𝐞 𝐫𝐢𝐠𝐡𝐭 𝐚𝐩𝐩𝐫𝐨𝐚𝐜𝐡. #Java #Multithreading #JavaDeveloper #BackendDevelopment #InterviewPreparation #SpringBoot #Concurrency