Mastering Java Arrays for Efficient Coding

📌 Day 18,19,20 – Understanding Arrays in Java On Day 18,19,20, I learned one of the most fundamental static data structures in Java — Arrays. 🔹 What is an Array? An array is an object used to store and retrieve multiple elements of the same data type efficiently. It helps organize data and enables faster access using index positions. 🔹 Key Observations About Arrays: Dimensionality → 1D, 2D, 3D arrays Homogeneous Data → Arrays store only the same data type Structure → Regular arrays & Jagged arrays 🔹 Array Syntax: int[] a = new int[5]; Arrays are created using the new keyword, which allocates memory in the Heap segment. 🔹 Important Concepts: Array index always starts from 0 Traversing elements from start to end is called array traversal Arrays are objects, not primitive data types 🔹 Types of Arrays: 1D Array → Single row structure 2D Array → Rows and columns 3D Array → Blocks, rows, and columns 🔹 Regular vs Jagged Array: Regular Array → Equal number of columns in every row Jagged Array → Unequal number of columns in rows 🔹 Returning an Array from a Method: When an array is returned from a method, the JVM creates an object, and the reference of that object is returned to the calling method. Understanding arrays builds a strong foundation for DSA, memory management, and real-world problem solving 🚀 #Java #CoreJava #Arrays #DataStructures #JVM #HeapMemory #LearningJourney #Day18

Day 25 of #100DaysOfLeetCode 💻✅ Solved #167. Two Sum II – Input Array Is Sorted on LeetCode using Java. Approach: • Used Two Pointer technique since the array is already sorted • Initialized one pointer at the beginning and one at the end • Calculated the sum of both elements • If sum < target, moved left pointer forward • If sum > target, moved right pointer backward • Returned 1-based indices as required in the problem Performance: ✓ Runtime: 1 ms (Efficient with O(n) time complexity) ✓ Memory: Constant extra space (O(1)) Key Learning: ✓ Understood when to apply Two Pointer technique instead of HashMap ✓ Improved ability to optimize space complexity ✓ Strengthened pattern recognition for sorted array problems Learning one problem every single day 🚀 #Java #LeetCode #DSA #TwoPointers #ProblemSolving #CodingJourney #100DaysOfCode

Day 33 of #100DaysOfLeetCode 💻✅ Solved #145. Binary Tree Postorder Traversal on LeetCode using Java. Approach: • Used recursion to perform postorder traversal • Followed Left → Right → Root order strictly • Traversed left subtree first • Then traversed right subtree • Added node value after visiting both subtrees Performance: ✓ Runtime: 0 ms (Beats 100.00% submissions) ✓ Memory: 43.12 MB (Beats 71.37% submissions) Key Learning: ✓ Clearly understood difference between preorder, inorder, and postorder ✓ Strengthened recursive tree traversal concepts ✓ Improved confidence in handling binary tree problems Learning one problem every single day 🚀 #Java #LeetCode #DSA #BinaryTree #Recursion #TreeTraversal #ProblemSolving #CodingJourney #100DaysOfCode

📅 Day 18 – Java Full Stack Development with AI Today I learned about String in Java. Topics covered: What is String Creating String object Common String methods (length(), charAt(), equals(), toUpperCase()) Key takeaway: Strings are objects in Java and are widely used to handle text data. #CoreJava #JavaString #JavaLearning #FullStackDeveloper #Day18

Learned something interesting about the char data type in Java today. I used to think char only stores characters. Turns out its numeric underneath. This small snippet made it obvious: char ch = 'A'; System.out.println(ch);   // output: A System.out.println(ch + 1);  // output: 66 'A' isn’t just a character, it has a numeric value (65). When Java performs arithmetic, it treats char as an integer. Tried this as well: char ch = '8'; System.out.println(ch); // output: 8 System.out.println((int) ch); // output: 56 That’s when ASCII / Unicode actually made sense instead of feeling like theory. Still learning the basics but understanding what’s happening underneath makes a big difference. #Java #LearningInPublic #Beginner #DSA

#Day47 of #100DaysDSAChallenge 🚀 Today I solved Reversing a Doubly Linked List in Java. 🔎 Brute Approach (Using Stack) Traverse the list, push node values into a stack, then overwrite values while popping to reverse the list data. Time Complexity: O(n) Space Complexity: O(n) ⚡ Better / Optimal Approach (In-place Pointer Swap) Swap prev and next for every node and update the head at the end. This reverses the actual structure without extra memory. Time Complexity: O(n) Space Complexity: O(1) 🔗 Solutions Repository: https://lnkd.in/g_rSFCh8 #100DaysOfDSA #DSA #LeetCode #Java #Algorithms #DataStructures #ProblemSolving #CodingJourney #LearningInPublic #InterviewPrep #PlacementPreparation #KunalKushwaha #Striver #GeeksForGeeks

Deep Dive into Java Fundamentals: Collections & Wrapper Classes ☕️ Today was all about strengthening the bedrock of my Java knowledge. I spent the day exploring the theoretical foundations of the Collection Interface, the Collections Utility Class, and Wrapper Classes. Understanding the "why" behind these concepts is just as important as the "how." Here’s a quick breakdown of my key takeaways: Collection vs. Collections: Clarified the distinction between the root interface for data structures and the utility class used for polymorphic algorithms (sorting, searching, etc.). Wrapper Classes: Diving into how Java wraps primitive data types into objects, enabling them to be used within the Collections Framework through Autoboxing and Unboxing. Data Structure Architecture: Looking at how different implementations (List, Set, Queue) handle data differently under the hood. Building a solid theoretical base is essential for writing efficient, scalable code. Back to the IDE to put these theories into practice! #Java #SoftwareDevelopment #JavaFullStack #CodingJourney #BackendDevelopment #ContinuousLearning

Learning 2D Arrays & Jagged Arrays in Java Recently explored the concepts of 2D arrays and jagged arrays in Java and focused on understanding how they actually work in memory. Key takeaways: • Each row is stored separately in memory • Jagged arrays allow different row sizes • Better understanding of references and dynamic allocation Visualizing the internal structure helped me strengthen my logical thinking and clarity in handling multidimensional data. Building strong fundamentals step by step with Harshit T at TAP Academy #Java #DataStructures #Arrays #JaggedArrays #ProgrammingFundamentals #LearningJourney #DeveloperGrowth

Solved two important Matrix problems in Java today 1. Set Matrix Zeroes Implemented a better approach using extra row and column arrays Then explored the optimal approach using the first row and column as markers Helped me understand space optimization concepts more clearly 2. Rotate Image (Matrix Rotation) First transposed the matrix (diagonal swapping logic) Then reversed each row to achieve 90° rotation Strengthened my understanding of in-place matrix manipulation Gradually becoming more comfortable with matrix problems in DSA. Trying to stay consistent and improve step by step 🙂 Code is available on my GitHub 👇 https://lnkd.in/g-Km2-kt If anyone has suggestions or knows a better approach, please feel free to share 🙌 #DSA #Java #MatrixProblems #ProblemSolving #CodingJourney #LearningInPublic #Consistency