S Alam’s Post

Day 40 | LeetCode Learning Journal 🚀 Today I solved Validate Binary Search Tree (BST) using a range-based recursive approach. This problem helped me deeply understand how BST properties apply to the entire tree, not just immediate children! 🔑 Key Points: • Checked whether a binary tree is a valid BST. • Maintained a valid range (min, max) for each node. • Ensured every node follows BST rules globally. • Used recursion to traverse and validate nodes. 🌱 What I Learned: • Importance of passing constraints (min/max) in recursion. • Difference between local vs global validation in trees. • Strengthened understanding of Binary Search Tree properties. • Improved recursive thinking for tree problems. #LeetCode #100DaysOfCode #DSA #CodingJourney #Day40 🚀

Day 2/100 of my LeetCode Journey Today I solved “Kth Largest Element in an Array.” Initially, I made a basic mistake. I approached it like a search problem, trying to find a specific value. But this problem is actually about position—finding the kth largest element in sorted order. That small shift in thinking made a big difference. What I learned: The same problem can be solved in multiple ways. Sorting is the simplest. Heaps are more efficient, and quickselect is even more optimized on average. I focused more on understanding why each approach works rather than just coding one solution. Takeaway: Sometimes the main difficulty is not coding, but understanding what the problem is really asking. Still a lot to improve, but making steady progress. Question: Do you usually stick to one approach or try to understand multiple ways to solve the same problem? #Day2 #LeetCode #DSA #LearningInPublic #Consistency

🚀 Day 29/100 — LeetCode Challenge Today's problem: Find First and Last Position of Element in Sorted Array 🧠 Concept: Binary Search (Boundary Finding) 💡 Key Idea: Use binary search twice to find the first and last occurrence of a target element in a sorted array. ⚡ Time Complexity: O(log n) 📂 Solutions Repository https://lnkd.in/gkFh2mPZ Understanding how to modify binary search to handle duplicates and find boundaries. #100DaysOfLeetCode #DSA #LeetCode #CodingChallenge #SoftwareEngineering

🚀 Day 26/100 – LeetCode Challenge ✅ Problem Solved: Valid Perfect Square Today’s problem was about checking whether a number is a perfect square without using any built-in functions like sqrt. I solved it using Binary Search, which helped efficiently determine whether there exists an integer whose square equals the given number. 💡 Key Learning: Binary Search can be applied beyond arrays Handling large numbers requires careful use of data types Avoiding overflow is important in mathematical problems ⚡ Complexity: Time: O(log n) Space: O(1) Learning to apply fundamentals in different ways every day 🚀 #Day26 #100DaysOfCode #LeetCode #DSA #Cpp #CodingJourney #BinarySearch #ProblemSolving

Day 29 – LeetCode Journey 🚀 Solved Two Sum II – Input Array Is Sorted using the Two Pointer technique, leveraging the sorted nature of the array for an optimal solution. 🔹 Time Complexity: O(n) 🔹 Runtime: 2 ms (Beats 96.37%) 🔹 Memory Usage: 48.58 MB This problem is a great reminder that recognizing patterns (like sorted arrays) can significantly reduce complexity and improve efficiency. Small optimizations, big impact 📈 Staying consistent and sharpening problem-solving skills every day. #LeetCode #DSA #ProblemSolving #CodingJourney #SoftwareEngineering #Consistency #Learning

🚀 Day 51 of my LeetCode Journey Solved: Roman to Integer At first glance, this problem looks simple — just map symbols to numbers. But the real catch is handling subtractive cases like IV (4), IX (9), etc. 💡 Key Learning: Instead of blindly adding values, you need to compare current and next characters: If current < next → subtract Else → add This small twist is what separates a correct solution from a wrong one. 📊 Result: ✅ Accepted ⏱️ Runtime: 6 ms 📌 Takeaway: Even “easy” problems test your attention to detail. Don’t underestimate them. Consistency > Motivation. See you on Day 52. #LeetCode #DSA #CodingJourney #ProblemSolving #Consistency

🧠 Day 32/75: Solving for the "End" from the "Beginning" Linked Lists can be tricky because you can't access elements by index. So, how do you remove the Nth element from the back without knowing the total length? Today’s LeetCode session was a deep dive into Pointer Logic. By maintaining a specific distance between two pointers, I was able to identify and delete the target node in a single traversal. Current Progress: 📅 32 Days Consecutive 🎯 Focus: Advanced Linked List Patterns ⚡ Result: 100% Beats Runtime Another day, another problem solved. The second month is off to a strong start! 💻🔥 #Consistency #100DaysOfCode #DSA #CodingJourney #JavaDeveloper #TechGrowth #LeetCodeChallenge #LinkedInLearning

🚀 Day 27/100 – LeetCode Challenge ✅ Problem Solved: Remove Duplicates from Sorted Array Today’s problem was a classic example of using the two-pointer technique. The goal was to remove duplicates from a sorted array in-place while maintaining the order of elements. I used two pointers to track unique elements and overwrite duplicates efficiently without using extra space. 💡 Key Learning: Two-pointer technique is very effective for array problems In-place operations help reduce space complexity Understanding problem constraints leads to optimal solutions ⚡ Complexity: Time: O(n) Space: O(1) Consistency is building confidence step by step 🚀 #Day27 #100DaysOfCode #LeetCode #DSA #Cpp #CodingJourney #TwoPointers #ProblemSolving

🚀 Day 28/100 – LeetCode Challenge ✅ Problem Solved: Third Maximum Number Today’s problem was about finding the third distinct maximum number in an array. If it doesn’t exist, we return the maximum number instead. I solved this using an optimized approach by tracking the top three distinct values in a single pass without using extra space. 💡 Key Learning: Handling distinct elements is important in many problems Maintaining multiple variables can replace sorting One-pass solutions improve efficiency significantly ⚡ Complexity: Time: O(n) Space: O(1) Consistency is turning effort into progress every day 🚀 #Day28 #100DaysOfCode #LeetCode #DSA #Cpp #CodingJourney #ProblemSolving

🚀 Day 26/100 — LeetCode Challenge Today's problem: Search in Rotated Sorted Array II 🧠 Concept: Binary Search with Edge Cases 💡 Key Idea: Duplicates can make it difficult to identify the sorted half. In such cases, shrink the search space from both ends. ⚡ Time Complexity: O(log n) average, O(n) worst case 📂 Solutions Repository https://lnkd.in/gkFh2mPZ A great example of how edge cases can complicate an otherwise straightforward approach. #100DaysOfLeetCode #DSA #LeetCode #CodingChallenge #SoftwareEngineering