Java Solution: Contains Duplicate II Problem on LeetCode

Day 75 of #100DaysOfLeetCode 💻✅ Solved #278. First Bad Version problem in Java. Approach: • Used Binary Search to minimize API calls • Narrowed search space using isBadVersion(mid) • Moved left/right pointers based on condition • Final position gives the first bad version Performance: ✓ Runtime: 16 ms (Beats 10.29% submissions) ✓ Memory: 42.16 MB (Beats 42.59% submissions) Key Learning: ✓ Practiced Binary Search with API-based problems ✓ Improved optimization by reducing unnecessary calls ✓ Strengthened problem-solving using monotonic conditions Learning one problem every single day 🚀 #Java #LeetCode #DSA #BinarySearch #ProblemSolving #CodingJourney #100DaysOfCode

🚀 Day 47/180 | #180DaysOfCode 📍 LeetCode | 💻 Java Solved: 448. Find All Numbers Disappeared in an Array Used an in-place marking technique by treating indices as a hash map and marking visited numbers as negative to identify missing elements. ⏱️ Time Complexity: O(n) 📦 Space Complexity: O(1) (excluding output list) Strengthening understanding of array manipulation and in-place hashing tricks. 💪 Consistency continues 🚀 #DSA #LeetCode #Java #CodingJourney #Consistency

Day 89 of #100DaysOfLeetCode 💻✅ Solved #15. 3Sum problem in Java. Approach: • Sorted the array first • Fixed one element and used Two Pointers for the rest • Skipped duplicates to avoid repeated triplets • Adjusted pointers based on sum comparison Performance: ✓ Runtime: 30 ms (Beats 87.77% submissions) ✓ Memory: 59.02 MB (Beats 77.30% submissions) Key Learning: ✓ Mastered Two Pointer technique with sorting ✓ Learned handling duplicates efficiently ✓ Improved problem-solving for combination-based problems Learning one problem every single day 🚀 #Java #LeetCode #DSA #TwoPointers #Arrays #Sorting #ProblemSolving #CodingJourney #100DaysOfCode

Day 88 - LeetCode Journey Solved LeetCode 24: Swap Nodes in Pairs in Java ✅ This problem is a great exercise in pointer manipulation in linked lists. Instead of changing values, I swapped the actual nodes by carefully adjusting the next pointers. Using a dummy node made the process much cleaner and helped handle edge cases smoothly. Step by step, I swapped pairs while moving forward in the list. Key takeaways: • Deep understanding of pointer manipulation • Importance of dummy node in linked list problems • Clean handling of edge cases • Iterative approach for swapping nodes ✅ All test cases passed ⚡ Efficient O(n) time and O(1) space Linked list problems like this really sharpen your fundamentals 🔥 #LeetCode #DSA #Java #LinkedList #Pointers #ProblemSolving #CodingJourney #InterviewPrep #Consistency #100DaysOfCode

🚀 Day 46/180 | #180DaysOfCode 📍 LeetCode | 💻 Java Solved: 2315. Count Asterisks Used a boolean flag approach to track whether the current position is inside a pair of '|' and count only the valid '*' outside those sections. ⏱️ Time Complexity: O(n) 📦 Space Complexity: O(1) Strengthening understanding of state-based string traversal and conditional counting. 💪 Consistency continues 🚀 #DSA #LeetCode #Java #CodingJourney #Consistency

Day 94/100 – Consistency Journey Today’s focus: Strings in DSA + Java Multithreading Practiced string problems involving sliding window, two pointers, and pattern-based thinking. Realized how much efficiency improves when you move from brute force to optimized approaches. On the backend side, explored ExecutorService in Java — understanding how thread pools help manage multiple tasks efficiently instead of creating threads manually every time. Key takeaway: DSA builds problem-solving mindset, while backend concepts like multithreading show how things actually scale in real-world systems. Slowly connecting both worlds. Consistency > Motivation. #Day94 #100DaysOfCode #DSA #Java #BackendDevelopment #LearningInPublic

🚀 Day 58/180 | #180DaysOfCode 📍 LeetCode | 💻 Java Solved: 278. First Bad Version Used binary search on answer space to efficiently find the first bad version while minimizing API calls. ⏱️ Time Complexity: O(log n) 📦 Space Complexity: O(1) Strengthening understanding of binary search optimization and decision-based problems. 💪 Consistency continues 🚀 #DSA #LeetCode #Java #CodingJourney #Consistency

Day 63 of #100DaysOfLeetCode 💻✅ Solved #2085. Count Common Words With One Occurrence problem in Java. Approach: • Iterated through each word in the first array • Avoided duplicate checks by ensuring each word is processed only once • Counted occurrences of the current word in both arrays • If the word appears exactly once in both arrays, incremented the result • Returned the final count Performance: ✓ Runtime: 88 ms (Beats 7.45% submissions) ✓ Memory: 46.06 MB (Beats 93.07% submissions) Key Learning: ✓ Practiced handling duplicates and frequency counting ✓ Improved understanding of string comparison in arrays ✓ Learned importance of optimizing nested loop solutions Learning one problem every single day 🚀 #Java #LeetCode #DSA #Strings #Arrays #ProblemSolving #CodingJourney #100DaysOfCode

🚀 Day 65/180 | #180DaysOfCode 📍 LeetCode | 💻 Java Solved: 2535. Difference Between Element Sum and Digit Sum of an Array Used a single loop + digit extraction approach to calculate both element sum and digit sum efficiently. ⏱️ Time Complexity: O(n × d) 📦 Space Complexity: O(1) Strengthening understanding of number manipulation and digit-based operations. 💪 Consistency continues 🚀 #DSA #LeetCode #Java #CodingJourney #Consistency

Day 72 of #100DaysOfLeetCode 💻✅ Solved #3866 “First Unique Even Element” problem in Java. Approach: • Traversed the array to find even numbers • For each even number, counted its occurrences in the array • If the count is exactly 1, returned that number • Continued until the first unique even number is found • Returned -1 if no such number exists Performance: ✓ Runtime: 1 ms (Beats 99.36% submissions) 🚀 ✓ Memory: 45.15 MB (Beats 98.39% submissions) Key Learning: ✓ Practiced combining conditions (even + uniqueness) ✓ Improved understanding of nested loop logic ✓ Learned how to filter and validate elements efficiently Learning one problem every single day 🚀 #Java #LeetCode #DSA #Arrays #ProblemSolving #CodingJourney #100DaysOfCode