Find Missing Numbers in Array using HashSet and Range Traversal

This problem uses a modified Binary Search to find a target in a rotated sorted array in O(log n) time. Key Idea: Even after rotation, one half of the array is always sorted. By identifying the sorted half and checking if the target lies within it, we can eliminate half of the search space in every step. => Time Complexity: O(log n) => Space Complexity: O(1) Great problem to strengthen binary search fundamentals and edge-case handling. #BinarySearch #Array #DivideAndConquer #LeetCode #DSA #InterviewPreparation #Java

Day 9/100 – LeetCode Challenge Problem: 3Sum Today’s challenge was to find all unique triplets in an array whose sum equals 0. Approach: Sort the array to efficiently apply the two-pointer technique. Fix one element nums[i] and use two pointers (left and right) to find the remaining two numbers. If the sum equals 0, store the triplet. Skip duplicate elements to ensure only unique triplets are included. Key Idea: Sorting + Two Pointers helps reduce the brute-force O(n³) approach to O(n²). Concepts Practiced: Sorting Two-pointer technique Duplicate handling Array traversal optimization #100DaysOfCode #LeetCode #DSA #Java #TwoPointers #ProblemSolving #CodingJourney

Day: 44/365 📌 LeetCode POTD: Count Binary Substrings Easy Key takeaways/Learnings from this problem: 1. The real trick is noticing you don’t need to check every substring — just track lengths of consecutive 0s and 1s. 2. Big takeaway: many string problems become simple once you focus on grouping patterns instead of brute force counting. #POTD #365DaysOfCode #DSA #Java #ProblemSolving #LearningInPublic #Consistency 🥷

Day: 43/365 📌 LeetCode POTD: Binary Number with Alternating Bits Easy Key takeaways/Learnings from this problem: 1. This one shows how clean bit tricks can replace messy string checks when working with binary patterns. 2. Big takeaway: sometimes a small observation (like using XOR or shifting) turns a pattern problem into a super neat one-liner. #POTD #365DaysOfCode #DSA #Java #ProblemSolving #LearningInPublic #Consistency 🥷

🚀 Day 23 of #100DaysOfCode 🌱 Topic: Strings / Hashing / Sliding Window ✅ Problem Solved: LeetCode 1461 – Check If a String Contains All Binary Codes of Size K 🛠 Approach: Generated all substrings of length k using sliding window. Stored each substring inside a HashSet to track uniqueness. Compared set size with 2^k to check if all possible binary codes exist. Used bit manipulation concept (1 << k) to calculate total combinations. ⏱ Time Complexity: O(n * k) 📦 Space Complexity: O(2^k) #100DaysOfCode #Day23 #DSA #Strings #Hashing #BitManipulation #Java #LeetCode #ProblemSolving #CodingJourney #Consistency #LearningInPublic #SoftwareEngineering

Day 36/100 – LeetCode Challenge 🚀 Problem: 3Sum Closest Approach: Sorted the array Fixed one element and applied the two-pointer technique Tracked the closest sum by comparing absolute differences Returned immediately if an exact match was found Time Complexity: O(n²) Space Complexity: O(1) Key takeaway: Many optimization problems are variations of classic patterns. Understanding 3Sum deeply makes solving 3Sum Closest straightforward. #LeetCode #100DaysOfCode #DSA #Java #TwoPointers #ProblemSolving #InterviewPrep

𝐃𝐚𝐲 𝟔/𝟑𝟔𝟓 🚀 📌 𝐆𝐅𝐆 𝐏𝐎𝐓𝐃: 𝐅𝐢𝐧𝐝 𝐊𝐭𝐡 𝐑𝐨𝐭𝐚𝐭𝐢𝐨𝐧 🔍 𝐊𝐞𝐲 𝐈𝐧𝐬𝐢𝐠𝐡𝐭 (𝐋𝐢𝐧𝐞𝐚𝐫 𝐒𝐜𝐚𝐧): In a rotated sorted array, the rotation count is the index of the minimum element. ➡ Scan the array ➡ The point where arr[i] > arr[i+1] indicates the rotation ➡ Answer is i + 1 👉 𝐓𝐢𝐦𝐞: O(n) 👉 𝐒𝐩𝐚𝐜𝐞: O(1) Consistency beats intensity. Learning in public. 💪 #POTD #GFG #365DaysOfCode #DSA #Java #Arrays #ProblemSolving 👨💻 🔗 Problem link in comments 👇

Day 35/100 – LeetCode Challenge 🚀 Problem: 3Sum Approach: Sorted the array Fixed one element and used two pointers for the remaining two Skipped duplicates to ensure unique triplets Used early stopping when the current number became positive Time Complexity: O(n²) Space Complexity: O(1) Key takeaway: Many 3-element sum problems reduce to sorting + two-pointer pattern. #LeetCode #100DaysOfCode #DSA #Java #TwoPointers #ProblemSolving #InterviewPrep

#Day_33_of_my_DSA_Journey (mission: abki bar string, array par) Today I solved the  Longest Consecutive Sequence in an Array problem using an (Optimized Approach) Instead of sorting the array (which would take O(n log n)), I used a HashSet to achieve O(1) lookups. ✅ Steps: ->Store all elements in a HashSet ->Only start counting when the current number is the start of a sequence (i.e., el - 1 does not exist in the set) ->Keep checking for consecutive numbers (el + 1) ->Track the maximum sequence length *Time Complexity: O(n) *Space Complexity: O(n) #DSA #Java #Coding #SoftwareDevelopment #ProblemSolving #LearningJourney

𝗬𝗼𝘂 𝗵𝗮𝘃𝗲 𝗯𝗲𝗲𝗻 𝘂𝘀𝗶𝗻𝗴 𝗕𝗶𝗻𝗮𝗿𝘆 𝗦𝗲𝗮𝗿𝗰𝗵 𝘄𝗿𝗼𝗻𝗴. It is not just for sorted arrays. The real definition — "Eliminate HALF the search space with each decision." That one shift in thinking unlocks 20+ LeetCode problems. Swipe to see the template, live code, and 7 problems you can now solve with one pattern. 👇 Save this. 🔖 #DSA #BinarySearch #Java #LeetCode #CodingInterview #DebugWithPurpose