LeetCode: Combination Sum 39 with Backtracking Approach

🔍 Day 66 of #100DaysOfCode 🔍 🔹 Problem: Binary Search – LeetCode ✨ Approach: Implemented an iterative binary search to efficiently locate the target element within a sorted array. By halving the search range each time — adjusting low and high around the mid-point — the algorithm achieves blazing-fast lookups! ⚡ 📊 Complexity Analysis: Time Complexity: O(log n) — array size halves with each iteration Space Complexity: O(1) — constant extra space ✅ Runtime: 0 ms (Beats 100.00%) ✅ Memory: 46.02 MB 🔑 Key Insight: Binary Search is proof that efficiency isn’t about doing more — it’s about eliminating what’s unnecessary. 🚀 #LeetCode #100DaysOfCode #ProblemSolving #DSA #AlgorithmDesign #BinarySearch #LogicBuilding #Efficiency #ProgrammingChallenge #CodeJourney #CodingDaily

🔢 Day 69 of #100DaysOfCode 🔢 🔹 Problem: Maximum Count of Positive and Negative Integers – LeetCode ✨ Approach: A simple yet powerful one-pass solution! Iterated through the array, counting positives and negatives separately — and returned whichever count was greater. Clean, direct, and efficient. ⚡ 📊 Complexity Analysis: Time Complexity: O(n) — single traversal of the array Space Complexity: O(1) — no extra data structures used ✅ Runtime: 1 ms (Beats 12.27%) ✅ Memory: 46.89 MB 🔑 Key Insight: Sometimes, simplicity wins — clarity in logic often outperforms complex tricks. Counting right leads to coding right! 💡 #LeetCode #100DaysOfCode #ProblemSolving #DSA #Array #AlgorithmDesign #LogicBuilding #CodeJourney #ProgrammingChallenge #CodingDaily #Efficiency

🚀 Day 2 of My #120DaysLeetCode Challenge – Add Two Numbers (Medium) Problem: You are given two non-empty linked lists representing two non-negative integers. Each node contains a single digit, and the digits are stored in reverse order — meaning the 1’s digit is at the head of the list. Your task is to add the two numbers and return the sum as a linked list (also in reverse order). 💡 Approach & Thought Process: To solve this problem, I broke it down into simple, logical steps: Initialize a dummy node to store the result list and use a current pointer to traverse. Keep track of the carry (since adding two digits can be more than 9). Traverse both linked lists simultaneously: Add corresponding digits from both lists along with the carry. Compute sum = val1 + val2 + carry. Update carry = sum / 10 and store sum % 10 as the new node value. Move to the next nodes in both lists until all nodes and carry are processed. Finally, return the linked list starting from the dummy’s next node. ⚙️ Key Concepts Used: Linked List traversal Carry management in addition Handling different lengths of linked lists 🧠 Learning Outcome: This problem helped me strengthen my understanding of linked list manipulation and how to simulate arithmetic operations through data structures. It was a great way to practice pointer handling and iterative problem-solving logic. #LeetCode #CProgramming #LinkedList #DataStructures #100DaysOfCode #CodingChallenge #ProblemSolving

🚀 LeetCode Daily Challenge Complete! Just solved "Find X-Sum of All K-Long Subarrays II" - Part II requires sophisticated two-set optimization! 💡 Solution Evolution: Naive Approach (TLE): ❌ Rebuild frequency map + heap for each window ❌ O(n × k × log k) - too slow for large inputs Optimized Two-Set Solution: ✅ Maintain two ordered sets: top (x elements) and bottom (rest) ✅ Track running sum of top set ✅ On element added: Update frequency, rebalance sets ✅ On element removed: Update frequency, rebalance from bottom ✅ O(n log n) - OPTIMAL! ✨ The key insight: Don't rebuild from scratch! Maintain top-x elements in an ordered set ordered by (frequency, value). When frequencies change, efficiently move elements between top and bottom sets. Running sum updates incrementally instead of recalculating! Critical operations: - Add: Insert to top, demote smallest if size > x - Remove: Delete from appropriate set, promote from bottom if needed - Both operations: O(log n) with set rebalancing Time: O(n×k×log k) → O(n log n) | Space: O(n) #LeetCode #HardProblems #CPlusPlus #Algorithms #SoftwareEngineering #ProblemSolving #TwoSetPattern #Optimization

🌟 Day 105 of My LeetCode Journey — Problem 138: Copy List with Random Pointer 💡 Problem Insight: Today’s problem took linked lists to a new level — each node had not just a next pointer but also a random pointer that could point to any node (or null). The challenge was to create a deep copy of such a list, preserving both connections perfectly. 🧠 Concept Highlight: The efficient approach involves three smart steps: Clone each node and insert it right next to the original node. Set up random pointers for the cloned nodes. Detach the two lists to restore the original and extract the copy. This clever interleaving technique avoids extra space (no hash map needed) and runs in O(n) time — an elegant display of pointer manipulation. 💪 Key Takeaway: Duplication isn’t about copying blindly — it’s about understanding the relationships and structure beneath the surface. ✨ Daily Reflection: This problem reinforced that clean logic and visualization make even the most pointer-heavy tasks simple and satisfying. #Day105 #LeetCode #100DaysOfCode #LinkedList #ProblemSolving #RandomPointer #DeepCopy #DSA #CodingJourney #LearnByDoing #SoftwareEngineering

#Day 24: #100DaysOfCodingChallenge 🔍✨ Back to fundamentals today with the classic Binary Search! Sometimes revisiting core algorithms reinforces why they're foundational—elegant, efficient, and essential for any programmer's toolkit. Every problem solved adds another brick 🧱 to the foundation! 🟢 LeetCode 704: Binary Search 🔹 Difficulty: Easy ⏱️ Time Complexity: O(log n) 💾 Space Complexity: O(1) 🕒 Time Taken: 0 ms 💡 Approach: Used two pointers (left and right) to define the search space. In each iteration, calculated mid and compared it with target—if equal, returned mid; otherwise, eliminated half the search space by updating pointers. The beauty lies in halving possibilities with each comparison!

🚀 Day-77 of #100DaysOfCodeChallenge Today’s problem: Delete Nodes From Linked List Present in Array (LeetCode 3217) 💻 Working with linked lists always reminds me that sometimes in code — and in life — you have to remove what’s not needed to keep things moving efficiently ✂️ This challenge was about filtering out nodes whose values existed in a given array — a perfect mix of logic, pointer manipulation, and careful iteration 🔁 ✨ What I learned today: Efficiently handling deletions in a linked list without breaking the chain Using hash sets to make lookups faster on LeetCode. The importance of clean and minimal traversal logic Some problems aren’t just about syntax — they’re about clarity of thought 🧠 Another green check ✅ Another step closer to consistency 💪 #100DaysOfCode #LeetCode #ProblemSolving #CodingJourney #DataStructures #Algorithms #LinkedList #DeveloperLife #CodeEveryday #JavaDeveloper #TechJourney

🔗 Day 75 of #100DaysOfCode 🔗 🌳 Problem: Binary Tree Postorder Traversal – LeetCode ✨ Approach: Implemented a recursive depth-first traversal that processes the left subtree, then right subtree, and finally the root node — perfectly matching the postorder pattern (Left → Right → Root). The solution is clean, intuitive, and highlights the elegance of recursion in tree traversal! 🌿 📊 Complexity Analysis: ⏱ Time Complexity: O(n) — each node is visited exactly once 💾 Space Complexity: O(n) — recursion stack in the worst case (skewed tree) ✅ Runtime: 0 ms (Beats 100% 🚀) ✅ Memory: 43.07 MB 💡 Key Insight: Recursion beautifully mirrors the natural hierarchy of trees — by trusting the call stack, we achieve simplicity and clarity in solving even complex traversal problems. 🌱 #LeetCode #100DaysOfCode #ProblemSolving #DSA #BinaryTree #Recursion #AlgorithmDesign #CodeJourney #ProgrammingChallenge #LogicBuilding #Efficiency #CodingDaily

New Statsig docs just went live 🎉 You can now directly connect to tools like Cursor or Codex by using the Statsig docs as an MCP server 🤩 This allows the tool to read our docs - helping coding agents use the correct Statsig syntax when setting up feature gates or experiments 🛠️ Oh, and we’ve also completely refreshed the UI across all docs pages! Thank you Mintlify 🤝 Watch PM Brock Lumbard's demo and head to our docs to try it out: https://lnkd.in/gbicptzC