Mastering Monotonic Stack for Efficient Problem Solving

🚀 Code 6 – #50LeetCodeChallenge 🧩 Problem: Search Insert Position Given a sorted array of distinct integers and a target value, return its index if found. If not, return the position where it should be inserted to maintain sorted order. 💡 Approach: Use Binary Search to efficiently locate the target or its correct insertion position in O(log n) time. 📚 Key Takeaway: Binary search is the go-to technique for problems involving sorted arrays, especially when optimal time complexity is required. #LeetCode #Java #Coding #ProblemSolving #BinarySearch #Arrays #Programming

How do you solve problems where you need to try every possible combination? This is where Backtracking comes in. In this short video, I explained: - What is backtracking - How it works (try → explore → undo) - Real-world examples like N-Queens and Sudoku - Importance of pruning Backtracking is a powerful approach for solving complex constraint-based problems. Explore structured DSA in Java roadmap + practice: www.quipoin.com #DSA #Java #Programming #Coding #SoftwareEngineering #Algorithms #InterviewPreparation

🚀 Day 15 of 180 — 3Sum Closest ✅ LeetCode 16 — 3Sum Closest First sort the array. Then fix one element and use two pointers for the remaining two — one at left, one at right. For every triplet I calculate the sum and check how far it is from the target: distance = |target - sum| If this distance is less than my current minimum difference, I update my answer. Moving pointers is simple — if sum is greater than target → move right pointer left if sum is less than target → move left pointer right if sum equals target → that's the closest it can get, return immediately The key thing I made sure — keep tracking the minimum difference throughout and update result whenever a closer sum is found. Day 15 done. 165 to go. 🔥 #180DaysDSA #Day15 #LeetCode #Java #DSA #TwoPointers #Sorting #ThreeSum #DSAJourney #CodingJourney #Programming #DataStructures #Algorithms #ProblemSolving #BuildInPublic #CodeNewbie #LearnToCode #100DaysOfCode #SoftwareDevelopment #Developer #StudentDeveloper #TechCommunity #LinkedInTech #CompetitiveProgramming

Day 50 #SDE sliding window and number generation (DP/math) problems. Solved: • Longest Substring with At Most K Distinct Characters • Ugly Numbers Key Learning: • “Longest Substring with At Most K Distinct Characters” is a classic variable sliding window problem where we maintain a window with at most k distinct characters using a hashmap. • “Ugly Numbers” can be solved efficiently using dynamic programming with multiple pointers, avoiding repeated factor checks. #LeetCode #DSA #SlidingWindow #DynamicProgramming #Algorithms #Java #SoftwareEngineering

🔥 Day 36 of #LeetCode Journey ✅ Problem: Minimum Distance Between Three Equal Elements I Today’s problem was about finding the minimum distance between three equal elements in an array. 💡 Key Idea: Instead of checking all combinations, we track indices efficiently: Store the last two occurrences of each number When a third occurrence appears, calculate the distance Keep updating the minimum distance 🧠 What I Learned: Optimizing from brute force to O(n) approach Using HashMap effectively for tracking indices Thinking in terms of patterns instead of combinations ⚡ Time Complexity: O(n) ⚡ Space Complexity: O(n) 🔍 Example: Input: [1,2,1,1,3,1] Output: 3 Small optimizations make a big difference 💡 Staying consistent and improving every day! #Java #DSA #LeetCode #CodingJourney #100DaysOfCode #Programming #ProblemSolving

🚀 Code 3 – #50LeetCodeChallenge Problem: 4Sum Given an array of integers and a target value, find all unique quadruplets that sum up to the target. Each element must be used only once, and the solution set should not contain duplicate combinations. 💡 Approach: Sort the array and use nested loops along with a two-pointer technique to find combinations efficiently. Skip duplicate elements to ensure only unique quadruplets are included. 📚 Key Takeaway: Combining sorting with the two-pointer approach helps reduce complexity and is highly effective for solving multi-sum problems like 4Sum. #LeetCode #Java #Coding #ProblemSolving #Arrays #TwoPointers #Programming

🚀 Day 76 — LeetCode Practice 🚀 Today’s problem: Count the Number of Consistent Strings 💡 What I learned today: • Used a boolean array to efficiently track allowed characters • Practiced character indexing (c - 'a') technique • Improved understanding of string traversal using nested loops • Learned how to optimize lookup operations to O(1) 🧠 Key Idea: Store all allowed characters in a boolean array. Then, for each word, check if every character exists in the allowed set. If yes → count it as a consistent string ✅ ⚡ Approach Highlights: • Preprocessing allowed characters • Iterating through each word • Breaking early for invalid characters (optimization) • Counting only valid strings 💻 Language Used: Java Consistency is the key 🔑 — improving step by step every day! #Day76 #LeetCode #Java #CodingJourney #ProblemSolving #100DaysOfCode #Programming #Learning

🚀 Code 7– #50LeetCodeChallenge 🧩 Problem: Plus One Given an array representing a large integer, increment the number by one and return the updated array of digits. 💡 Approach: Traverse the array from the end and handle the carry: • If the digit is less than 9, simply increment and return • If the digit is 9, set it to 0 and continue • If all digits are 9, create a new array with an extra digit at the front. 📚 Key Takeaway: Handling carry efficiently is key in digit-based problems, especially when working with large numbers represented as arrays. #LeetCode #Java #Coding #ProblemSolving #Arrays #Math #Programming

Understanding arrays is not enough knowing how to operate on them is key. In this short video, I covered: - Traversal (O(n)) - Insertion (O(1) at end, O(n) in middle) - Deletion (O(1) at end, O(n) in middle) - Why shifting elements impacts performance These fundamentals help in choosing the right data structure and writing optimized code. Explore structured DSA in Java roadmap + practice: www.quipoin.com #DSA #Java #Programming #Coding #SoftwareEngineering #DataStructures #Algorithms

Day 41 #SDE stack-based validation and dynamic programming on strings. Solved: • Bracket Challenge • Word Break Key Learning: • “Bracket Challenge” reinforces the use of a stack to validate balanced parentheses and handle nested structures efficiently. • “Word Break” revisited the DP + memoization approach, where we check valid segmentations of a string using a dictionary. #LeetCode #DSA #Stack #DynamicProgramming #Algorithms #Java #SoftwareEngineering