Java DSA Day 38: Strings & Two-Pointer Technique

🚀 Day 41 / 180 – DSA with Java 🚀 📘 Topic Covered: Matrices & Marking Technique 🧩 Problem Solved: Set Matrix Zeroes Problem: Given a matrix, if an element is 0, set its entire row and column to 0. Approach: Used two auxiliary arrays to mark rows and columns that contain zeroes. In a second pass, updated the matrix by setting elements to zero based on the marked rows and columns. Key Learning: ✔️ Handling matrix-based transformations ✔️ Using extra space for clarity and simplicity ✔️ Breaking the problem into marking and updating phases If you’re also preparing for DSA, let’s connect and learn together 🤝 #DSA #Java #180DaysOfCode #LearningInPublic #Arrays #ProblemSolving #Consistency

🚀 Day 40 / 180 – DSA with Java 🚀 📘 Topic Covered: Binary Exponentiation (Fast Power) 🧩 Problem Solved: Pow(x, n) Problem: Implement a function to calculate x raised to the power n, handling both positive and negative values of n. Approach: Used Binary Exponentiation to reduce time complexity. Repeatedly squared the base and halved the exponent, multiplying the result only when needed. Also handled negative powers by taking the reciprocal. Key Learning: ✔️ Optimizing from O(n) to O(log n) ✔️ Understanding divide-and-conquer in exponentiation ✔️ Handling edge cases like negative powers If you’re also preparing for DSA, let’s connect and learn together 🤝 #DSA #Java #180DaysOfCode #LearningInPublic #ProblemSolving #Consistency 

🚀 Day 36 / 180 – DSA with Java 🚀 📘 Topic Covered: Binary Search (Peak Finding) 🧩 Problem Solved: Find Peak Element Problem: Given an array, find a peak element (an element greater than its neighbors) and return its index. Approach: Used Binary Search by comparing the middle element with its neighbors. Based on the increasing or decreasing slope, moved towards the side where a peak must exist, reducing the search space efficiently. Key Learning: ✔️ Applying binary search on unsorted arrays using patterns ✔️ Understanding how slope direction guides decisions ✔️ Solving peak problems in O(log n) time If you’re also preparing for DSA, let’s connect and learn together 🤝 #DSA #Java #180DaysOfCode #LearningInPublic #BinarySearch #ProblemSolving #Consistency

🚀 Day 43 / 180 – DSA with Java 🚀 📘 Topic Covered: Linked List Traversal 🧩 Problem Solved: Middle of the Linked List Problem: Given the head of a singly linked list, return the middle node. If there are two middle nodes, return the second middle node. Approach: Traversed the linked list once to count the total number of nodes. Then moved again up to the middle position and returned that node. Key Learning: ✔️ Practicing linked list traversal logic ✔️ Handling even-length edge cases correctly ✔️ Exploring multi-pass solutions before optimizing further If you’re also preparing for DSA, let’s connect and learn together 🤝 #DSA #Java #180DaysOfCode #LearningInPublic #LinkedList #ProblemSolving #Consistency

🚀 Day 46 / 180 – DSA with Java 🚀 📘 Topic Covered: Matrix Manipulation 🧩 Problem Solved: Rotate Image Problem: Given an n x n matrix representing an image, rotate it 90 degrees clockwise in-place. Approach: First transposed the matrix by swapping rows and columns across the diagonal. Then reversed each row to complete the 90-degree clockwise rotation efficiently without extra space. Key Learning: ✔️ Breaking matrix problems into smaller transformations ✔️ Understanding transpose operations ✔️ Solving in-place matrix rotation with O(1) extra space If you’re also preparing for DSA, let’s connect and learn together 🤝 #DSA #Java #180DaysOfCode #LearningInPublic #Matrix #ProblemSolving #Consistency 💙

🚀 Day 42 / 180 – DSA with Java 🚀 📘 Topic Covered: Linked List Traversal 🧩 Problem Solved: Find Middle of Linked List Problem: Given the head of a linked list, find and return the middle node’s value. Approach: First traversed the linked list to calculate its length. Then traversed again up to the middle index to retrieve the middle node. Key Learning: ✔️ Understanding linked list traversal ✔️ Breaking problems into multiple passes ✔️ Thinking about optimized approaches (like slow-fast pointers) If you’re also preparing for DSA, let’s connect and learn together 🤝 #DSA #Java #180DaysOfCode #LearningInPublic #LinkedList #ProblemSolving #Consistency

🚀 Day 37 / 180 – DSA with Java 🚀 📘 Topic Covered: Arrays & Two-Pointer Technique 🧩 Problem Solved: Squares of a Sorted Array Problem: Given a sorted array of integers (including negatives), return a new array of the squares of each number, also sorted in non-decreasing order. Approach: Used a two-pointer approach from both ends of the array. Compared squares of elements and filled the result array from the end to maintain sorted order efficiently. Key Learning: ✔️ Handling negative values in sorted arrays ✔️ Using two-pointer technique for optimal solutions ✔️ Avoiding extra sorting to achieve O(n) time complexity If you’re also preparing for DSA, let’s connect and learn together 🤝 #DSA #Java #180DaysOfCode #LearningInPublic #Arrays #ProblemSolving #Consistency 

🚀 Java DSA Progress Update I’ve solved 125/310 problems (~40%) as part of my structured Java DSA roadmap. ✔️ Strong in: Arrays, Strings, Linked Lists, Binary Search ⚡ Focusing next on: Heap, Graphs, Dynamic Programming, Sliding Window 📌 Approach: Pattern-based problem solving Time & space analysis Learning from mistakes Re-solving for retention 🎯 Goal: Become interview-ready in 30 days with strong problem-solving fundamentals. Consistent progress > perfection. #Java #DSA #LeetCode #ProblemSolving #SoftwareEngineering

🚀 Day 44 / 180 – DSA with Java 🚀 📘 Topic Covered: Binary Search on Answer 🧩 Problem Solved: Koko Eating Bananas Problem: Given banana piles and limited hours, find the minimum eating speed required to finish all piles within the given time. Approach: Applied Binary Search on the possible eating speed range. For each speed, calculated total hours needed and adjusted the search space until finding the minimum valid speed. Key Learning: ✔️ Understanding binary search beyond arrays ✔️ Applying search on answer space efficiently ✔️ Solving optimization problems in O(n log m) time If you’re also preparing for DSA, let’s connect and learn together 🤝 #DSA #Java #180DaysOfCode #LearningInPublic #BinarySearch #ProblemSolving #Consistency

🚀 Day 47 / 180 – DSA with Java 🚀 📘 Topic Covered: Matrix Traversal 🧩 Problem Solved: Spiral Matrix Problem: Given a matrix, return all elements in spiral order starting from the top-left corner. Approach: Used four boundaries — top, bottom, left, and right. Traversed layer by layer in four directions (left to right, top to bottom, right to left, bottom to top) while shrinking the boundaries after each pass. Key Learning: ✔️ Managing boundaries in matrix traversal ✔️ Breaking complex movement into clear steps ✔️ Handling edge cases in rectangular matrices If you’re also preparing for DSA, let’s connect and learn together 🤝 #DSA #Java #180DaysOfCode #LearningInPublic #Matrix #ProblemSolving #Consistency