Optimizing Code with Clean Thinking and Recursion

Day 60 of My 90-Day Coding Challenge Today I worked on a classic recursion + backtracking problem — and it really tested how well I understand breaking problems into smaller decisions. At first, it feels messy: multiple partitions, multiple choices, and many possible paths. But once you start thinking in terms of: -“Try every possible cut and validate it” the structure becomes clear. Key learning: • Recursion is about exploring all paths, not rushing to the answer • Validity checks (like palindrome here) are what control the tree • Clean backtracking (add → recurse → remove) is everything One thing that really helped today: Even if you don’t know where to start, just begin drawing the recursion tree. As you expand it step by step, the logic starts revealing itself — what choices to make, when to stop, and how to backtrack. What stood out today: Clarity in recursion doesn’t come from memorizing patterns — it comes from visualizing the process. Still improving. #90DaysOfCode #DSA #Java #Recursion #Backtracking #LeetCode #ProblemSolving

Day 19 of #100DaysOfCode Solved “Base 7” problem today — a simple yet insightful exercise on number systems. 💡 Approach: Convert the integer into base 7 by repeatedly dividing by 7 and storing remainders. Handle negative numbers separately and reverse the result at the end. ⚡ Key Learning: Even easy problems strengthen fundamentals like loops, math logic, and edge case handling. Consistency > Complexity. #LeetCode #DSA #CodingJourney #Java #ProblemSolving #100DaysOfCode

🚀 Day 16 of LeetCode Problem Solving Solved today’s problem — LeetCode #26: Remove Duplicates from Sorted Array 💻🔥 ✅ Approach: Two Pointers ⚡ Time Complexity: O(n) 📊 Space Complexity: O(1) The task was to remove duplicates in-place from a sorted array and return the count of unique elements. 👉 I used the Two Pointer technique: One pointer to track unique elements Another to traverse the array 💡 Key Idea: Since the array is sorted, duplicates will be adjacent — making it easier to skip them. 👉 Core Logic: Compare nums[i] with nums[j] If different → move pointer and update value Maintain unique elements at the beginning 💡 Key Learning: Two Pointer is a very powerful technique for array problems — especially when data is sorted. Consistency is the key — getting better every day 🚀 #Day16 #LeetCode #DSA #Java #CodingJourney #ProblemSolving #100DaysOfCode

🚀 Day 69 — LeetCode Practice 🚀 Today’s focus was on string manipulation and careful indexing. ✅ Problem solved today: 🔹 Find Common Characters 💡 Key learnings from today: • Understood how to find common characters across multiple strings • Learned the importance of character frequency counting • Practiced handling nested loops efficiently • Realized how small mistakes in indexing can affect the entire logic • Improved attention to detail while working with strings Initially, I made a mistake by using the wrong variable inside charAt(). This caused incorrect indexing, which can either lead to wrong output or even StringIndexOutOfBoundsException. After fixing it, the logic worked perfectly by correctly comparing characters and tracking their minimum frequency across all words. This problem reinforced an important lesson: Sometimes errors are not in logic — but in small details like indexing and variable usage. Accuracy matters as much as logic. Step by step, getting better 💪 On to Day 70 🚀 #Day69 #DSA #LeetCode #ProblemSolving #Java #CodingJourney #Consistency #FutureEngineer

🚀 Day 37 of My Coding Journey Today, I solved an interesting problem on array manipulation where I learned how to efficiently build a target array using given index positions. Instead of manually handling shifts, I used a loop along with dynamic data structures to simplify insertion and maintain clean logic. This helped me better understand the importance of choosing the right data structure to reduce complexity. 💡 Key takeaway: Using the right approach can turn a complex problem into a simple one. #Day37 #CodingJourney #Java #DSA #ProblemSolving #LeetCode #LearningInPublic

60-Day LeetCode Challenge – Day 40 Solved Check if All Characters Have Equal Number of Occurrences on LeetCode. 📌 Approach: Used a frequency array (size 26) to count occurrences of each character, then compared all non-zero frequencies with an expected value. 🧠 Learning: Reinforced frequency counting patterns — a super common technique in string problems. ⚡ Complexity: • Time Complexity: O(n) • Space Complexity: O(1) Starting to see patterns repeat across problems — that’s when things begin to click ⚡ #LeetCode #DSA #Java #Strings #Consistency #ProblemSolving

🚀 Day 44/100 Today’s problem: Reverse Vowels of a String. 🔹 Problem Summary: Given a string, reverse only the vowels while keeping other characters in the same position. 🔹 Approach I Used: I applied the Two Pointer Technique: - One pointer from the start, one from the end - Move both until vowels are found - Swap them and continue 🔹 Key Learning: ✔ Two pointers can simplify string problems a lot ✔ Always break the problem into smaller steps ✔ Practice improves pattern recognition. 🔹 Example: Input: "IceCreAm" Output: "AceCreIm" 🔹 Time Complexity: O(n) 🔹 Space Complexity: O(n) Consistency is the key 🔑 — showing up every day! #Day44 #CodingJourney #DSA #Java #Learning #100DaysOfCode

Day 5 / 100 Days of Coding : Solved: Best Time to Buy and Sell Stock Today’s problem looked simple but taught a powerful concept — tracking minimums and maximizing profit in a single pass. Key Learning: Instead of checking all pairs (which is slow), we maintain: Minimum price so far Maximum profit so far This reduces complexity from O(n²) → O(n) Consistency is the real game. Showing up every day matters more than perfection. #100DaysOfCode #DSA #LeetCode #Java #CodingJourney #ProblemSolving #GreedyAlgorithm

Day 22/100 — LeetCode Today’s problem: Happy Number 😊 At first, it looked like a simple math problem… but it turned out to be about patterns and repetition. 🔍 What I learned: Break a number into digits using % 10 and / 10 Square each digit and keep adding Repeat the process until: You reach 1 → Happy Number ✅ Or it starts repeating → Not Happy ❌ 🧠 Key Insight: This problem is actually about cycle detection — if a number repeats, it will never reach 1. ⚡ Simple Example: 19 → 82 → 68 → 100 → 1 ✅ 💡 Takeaway: Sometimes problems that look like math are really about loops and patterns. Small steps every day → Big improvement 🚀 #Day22 #100DaysOfCode #LeetCode #Java #DSA #CodingJourney

🚀 Day 11/100 — #100DaysOfLeetCode Consistency continues — one problem closer to better problem-solving skills 💻🔥 ✅ Problem Solved: 🔹 LeetCode 1423 — Maximum Points You Can Obtain from Cards 💡 Concepts Used: Sliding Window Technique Complementary Subarray Thinking 🧠 Key Learning: Instead of directly choosing k cards from both ends, I learned to think differently — find the minimum sum subarray of size n - k and subtract it from the total sum. This transformation converts a complex decision problem into a clean sliding window optimization. ⚡ Takeaway: Sometimes optimization comes from changing perspective, not increasing complexity. Continuing the journey 🚀 #100DaysOfLeetCode #LeetCode #DSA #SlidingWindow #Algorithms #Java #ProblemSolving #CodingJourney #LearningInPublic