LeetCode Practice: To Lower Case with Java

🚀 Day 55 of #100DaysOfCode — Getting Started with Multithreading in Java Over the past 2 days, I explored one of the most important concepts in Java: Multithreading 🔥 💡 What I Learned 🧵 What is Multithreading? Multithreading allows a program to execute multiple tasks simultaneously, improving performance and efficiency ⚡ 👉 Instead of running tasks one after another, we can run them in parallel. ⚙️ Creating Threads in Java 1️⃣ Using Thread Class Extend the Thread class Override the run() method Start using start() 2️⃣ Using Runnable Interface (Best Practice ✅) Implement Runnable Pass it to a Thread object Start execution using start() 🧠 Key Takeaways ✔ Runnable is preferred over Thread (better design & flexibility) ✔ Supports multiple inheritance ✔ Separates task from execution ✔ Helps in building scalable backend systems ⚠️ Important Concept 👉 Difference between: run() ❌ (normal method call) start() ✅ (creates new thread) 🔥 Real-World Use Cases Backend APIs Payment systems Real-time applications Inventory & billing systems (like the one I'm building 🏪) 🚀 What’s Next? ➡️ Synchronization ➡️ Race Conditions ➡️ ExecutorService (Thread Pool) Learning multithreading feels like unlocking a new level in Java 💪  Huge thanks to my mentor Suresh Bishnoi for simplifying complex concepts like multithreading and pushing me to keep learning consistently. #Java #Multithreading #100DaysOfCode #BackendDevelopment #LearningJourney

Day 98 - LeetCode Journey Solved LeetCode 20: Valid Parentheses in Java ✅ A classic stack problem that looks simple but tests your attention to detail. The idea is straightforward: Push opening brackets into stack and match them correctly when a closing bracket appears. If anything mismatches → invalid. Clean logic, zero confusion 💡 Key takeaways: • Stack fundamentals • Matching pairs efficiently • Handling edge cases (empty stack, wrong order) • Writing clean conditional logic ✅ All test cases passed ⚡ O(n) time and O(n) space Sometimes basics like this are the real building blocks of strong DSA 🔥 #LeetCode #DSA #Java #Stack #ProblemSolving #CodingJourney #InterviewPrep #Consistency #100DaysOfCode

Day 94 - LeetCode Journey Solved LeetCode 35: Search Insert Position in Java ✅ Classic Binary Search problem that tests your fundamentals. Instead of just finding the element, the twist is to return the correct insert position if it’s not present. The key idea is simple: keep narrowing the search space and finally return low, which represents the right position. Clean logic, high impact 💡 Key takeaways: • Strong grip on Binary Search fundamentals • Understanding search space boundaries • Returning correct insertion index • Writing efficient O(log n) solutions ✅ All test cases passed ⚡ O(log n) time and O(1) space Mastering basics like Binary Search is what builds real problem-solving strength 🔥 #LeetCode #DSA #Java #BinarySearch #ProblemSolving #CodingJourney #InterviewPrep #Consistency #100DaysOfCode

🚀 #Day52 of Java Series: Second Largest Element in an Array: 🔹 Logic (Simple Steps) 1️⃣ Take two variables: largest secondLargest 2️⃣ Loop through the array 3️⃣ For each number: If it's bigger than largest → update both values Else if it's smaller than largest but bigger than secondLargest → update secondLargest 4️⃣ Final answer will be in secondLargest 📌 Example Array: [12, 35, 1, 10, 34, 1] Output: 34 #Java #Arrays #SecondLargest #Developer #LinkedinPost #Day52 #Coding 10000 Coders Raviteja T Abdul Rahman

#repost Day1 - 𝐒𝐦𝐚𝐥𝐥 𝐂𝐨𝐧𝐜𝐞𝐩𝐭, 𝐁𝐢𝐠 𝐈𝐦𝐩𝐚𝐜𝐭 – 𝐉𝐚𝐯𝐚 𝐈𝐧𝐝𝐞𝐱𝐢𝐧𝐠 💡 In Java, array index starts from 0 because it represents the distance (offset) from the starting point in memory. 👉 Index 0 → First element (0 steps from start) 👉 Index 1 → Second element (1 step away) This makes calculations simple and fast: 𝑨𝒅𝒅𝒓𝒆𝒔𝒔 = 𝑩𝒂𝒔𝒆 + (𝑰𝒏𝒅𝒆𝒙 × 𝑺𝒊𝒛𝒆) 💡 Starting from 0 𝐚𝐯𝐨𝐢𝐝𝐬 𝐞𝐱𝐭𝐫𝐚 𝐜𝐚𝐥𝐜𝐮𝐥𝐚𝐭𝐢𝐨𝐧𝐬 𝐚𝐧𝐝 𝐢𝐦𝐩𝐫𝐨𝐯𝐞𝐬 𝐩𝐞𝐫𝐟𝐨𝐫𝐦𝐚𝐧𝐜𝐞. That’s why most languages follow 0-based indexing. #java #coding #developer #learning #springboot

Leetcode Practice - 3. Longest Substring Without Repeating Characters The problem is solved using JAVA. Start from first letter Keep adding letters until you see a duplicate When duplicate comes → move start forward Keep track of maximum length #LeetCode #Java #StringHandling #CodingPractice #ProblemSolving #DSA #DeveloperJourney #TechLearning

Day 35/100 – Exploring ListIterator in Java 🔁 Today I explored the use of ListIterator in Java while working with ArrayList. Unlike a normal iterator, ListIterator allows traversal in both directions, making it more flexible when working with lists. Key learnings: • Traverse elements using next() • Move backward using previous() • Check elements using hasNext() and hasPrevious() • Useful for bidirectional iteration and modifications Understanding different ways to iterate through data structures helps in writing more efficient and flexible code. Learning something new every day, one step at a time. 🚀 #100DaysOfCode #Java #ArrayList #DataStructures #CodingJourney #LearningInPublic

🚀 Back with another update from my Java + DSA journey! Staying consistent and focusing on building strong fundamentals 💪 Today I explored some core Java concepts: • Variable Shadowing Local variable hides class variable depending on scope • Static vs Non-Static Static → belongs to class (no object needed) Non-static → belongs to object (object required) • Variable Arguments (Varargs) Allows flexible number of inputs Fixed parameters come first, varargs must be last • Method Overloading Same method name, different parameters Java decides based on number/type of arguments 💡 Key takeaway: Understanding scope and function behavior makes coding much clearer. Small concepts, strong foundation 🔥 Let’s keep learning 🚀 #Day2 #Java #DSA #LearningInPublic #Consistency #CodingJourney

Day 92 - LeetCode Journey Solved LeetCode 143: Reorder List in Java ✅ This problem looks tricky at first, but once you break it into steps, it becomes clean and elegant. The idea is simple: 1️⃣ Find the middle of the list (slow-fast pointers) 2️⃣ Reverse the second half 3️⃣ Merge both halves alternately That’s it. Three steps, one solid solution. Key takeaways: • Mastering slow & fast pointer technique • In-place reversal of linked list • Merging two lists efficiently • Breaking complex problems into smaller parts ✅ All test cases passed ⚡ O(n) time and O(1) space Problems like this build real confidence in linked lists 💯 #LeetCode #DSA #Java #LinkedList #ProblemSolving #CodingJourney #InterviewPrep #Consistency #100DaysOfCode

☕ Learn Java with Me — Day 8 One variable for every value? That gets messy very fast. Today we learned something that makes code much smarter: 👉 Arrays in Java Instead of this: int a = 10; int b = 20; int c = 30; We can simply write: int[] numbers = {10, 20, 30}; Simple. Cleaner. Much more efficient. This is where Java starts feeling practical. From basics → real logic building 🚀 Week 2 already feels exciting. We’re learning together 🤝 #java #coding #arrays #learning #showup