Java Solution for LeetCode's Swap Nodes in Pairs Problem

Day 26 of #100DaysOfLeetCode 💻✅ Solved #203. Remove Linked List Elements on LeetCode using Java. Approach: • Handled edge cases by removing matching nodes from the beginning of the list • Traversed the linked list using a pointer • Checked the next node’s value instead of the current node • If value matched, updated links to skip the node • Maintained in-place modification without using extra data structures Performance: ✓ Runtime: 1 ms (Beats 95.94% submissions) ✓ Memory: 47.62 MB Key Learning: ✓ Improved understanding of linked list pointer manipulation ✓ Learned how to handle head node edge cases carefully ✓ Strengthened in-place deletion logic in singly linked lists Learning one problem every single day 🚀 #Java #LeetCode #DSA #LinkedList #ProblemSolving #CodingJourney #100DaysOfCode

Day 23 of #100DaysOfLeetCode 💻✅ Solved #19. Remove Nth Node From End of List on LeetCode using Java. Approach: • Used a dummy node to handle edge cases (like removing the head) • Initialized two pointers: fast and slow • Moved fast pointer n+1 steps ahead to maintain a gap • Traversed both pointers together until fast reached null • Slow pointer stopped just before the node to delete • Updated links to remove the target node in one pass Performance: ✓ Runtime: 0 ms (Beats 100% submissions) ✓ Memory: 43.77 MB Key Learning: ✓ Mastered two-pointer (fast & slow) technique ✓ Understood importance of dummy node for edge cases ✓ Solved the problem in a single traversal (O(n) time, O(1) space) Consistency is building confidence 🚀 #Java #LeetCode #DSA #LinkedList #TwoPointers #ProblemSolving #100DaysOfCode

Day 20 of #100DaysOfLeetCode 💻✅ Solved #21. Merge Two Sorted Lists problem on LeetCode in Java. Approach: • Handled edge cases where either list is empty • Used a dummy node to simplify merging logic • Maintained a pointer current to build the new list step-by-step • Compared nodes from both lists and linked the smaller one • Connected any remaining nodes after one list ends • Returned dummy.next as the new head of the merged list Performance: ✓ Runtime: 0 ms (Beats 100% submissions) ✓ Memory: 44.26 MB (Beats 75% submissions) Key Learning: ✓ Strengthened understanding of linked list pointer manipulation ✓ Learned to merge two lists without creating extra nodes ✓ Improved confidence in multi-pointer problems and list traversal Learning one problem every single day 🚀 #Java #LeetCode #DSA #ProblemSolving #CodingJourney #100DaysOfCode

Day 39 of #100DaysOfLeetCode 💻✅ Solved #258. Add Digits problem in Java. Approach: • Used a loop to repeatedly add all digits of the number • Extracted each digit using modulus (%) and divided the number by 10 • Stored the digit sum and repeated the process until the result became a single digit • Returned the final single digit as the answer Performance: ✓ Runtime: 1 ms (Beats 97.92% submissions) ✓ Memory: 42.52 MB Key Learning: ✓ Practiced digit extraction using modulus and division ✓ Understood how to repeatedly reduce a number to a single digit ✓ Strengthened problem-solving using loops and basic number manipulation Learning one problem every single day 🚀 #Java #LeetCode #DSA #ProblemSolving #CodingJourney #100DaysOfCode

Day 21 of #100DaysOfLeetCode 💻✅ Solved #27. Remove Element problem on LeetCode in Java. Approach: • Used a two-pointer technique to modify the array in-place • Maintained a pointer k to place elements not equal to val • Iterated through the array and skipped elements equal to val • Placed non-val elements at the k-th position and incremented k • Returned k as the number of remaining elements Performance: ✓ Runtime: 0 ms (Beats 100% submissions) ✓ Memory: 44 MB (Beats ~75% submissions) Key Learning: ✓ Strengthened understanding of in-place array manipulation ✓ Learned how to skip unwanted elements efficiently ✓ Improved confidence in two-pointer techniques for array problems Learning one problem every single day 🚀 #Java #LeetCode #DSA #ProblemSolving #CodingJourney #100DaysOfCode

Day 84/365 ✔️ Solved LeetCode 26 – Remove Duplicates from Sorted Array using Java. A classic two-pointer problem that looks simple but really tests how well you handle in-place updates. Key takeaways from today: • Leveraged the two-pointer technique • Modified the array in-place with O(1) extra space • Preserved the relative order of elements • Reinforced how sorted arrays simplify logic Consistency > intensity. One problem a day, building strong fundamentals. On to the next 🚀 #Day84 #365DaysOfCode #LeetCode #Java #DSA #TwoPointers #ProblemSolving #Consistency

🚀 Day 73 / 100 Days of LeetCode Question: Check if Binary String Has at Most One Segment of Ones Given a binary string s, determine whether it contains at most one continuous segment of '1's. Solved in Java by checking whether the pattern "01" exists in the string. If "01" appears, it means a new segment of 1s starts after a 0, which violates the condition. This provides a clean and efficient solution. Consistency > perfection. Day 74 loading 🔥 #100DaysOfCode #LeetCode #Java #DSA #ProblemSolving

🚀 Day 94 of #100DaysOfCode Solved LeetCode #762 – Prime Number of Set Bits in Binary Representation ✅ A neat problem combining bit manipulation with a simple prime check. Key Takeaways: -> Using Integer.bitCount() for efficient set-bit counting -> Applying basic prime validation on computed bits -> Clean iteration over a given range Simple logic, but great for reinforcing bitwise fundamentals Language: Java -> Runtime: 4 ms (Beats 87.21%) ⚡ -> Memory: 42.28 MB Consistency is stacking up day by day. On to the next one. 💻🔥 #LeetCode #Java #BitManipulation #PrimeNumbers #ProblemSolving #100DaysOfCode

Day 23 of #100DaysOfLeetCode Challenge ✅ 📌 Problem: String to Integer (atoi) – LeetCode #8 📊 Difficulty: Medium 💻 Language: Java Today I solved the classic atoi problem, which focuses on: Handling leading whitespaces Managing + / - signs correctly Converting digits safely Preventing 32-bit integer overflow & underflow ⚡ Performance: Runtime: 1 ms (Beats ~99%) Memory efficient solution This problem really tests edge case handling and string parsing logic, which is crucial for real-world input validation. Consistency over motivation — showing up every day matters. 💪 #Day23 #LeetCode #100DaysOfCode #Java #DSA #ProblemSolving #CodingJourney #Consistency #SoftwareEngineering

Day 13/100 – LeetCode Challenge 🚀 Problem: #283 Move Zeroes   Difficulty: Easy   Language: Java   Approach: Repeated Swapping / Zero Bubbling   Time Complexity: O(n²)   Space Complexity: O(1) 🔍 Key Insight: The goal is to move all **0s to the end** of the array while keeping the **relative order of non-zero elements unchanged**. Instead of creating a new array, the problem requires solving it **in-place**. 🧠 Solution Brief: First counted the total number of zeroes in the array. Then repeatedly traversed the array and whenever a **0** was found, swapped it with the next element. This process gradually pushes all zeroes toward the end of the array while preserving the order of the remaining elements. 📌 What I Learned: Even simple array problems require careful handling of constraints like **in-place modification** and **order preservation**. These problems also highlight the importance of thinking about **time complexity optimizations** for better performance. #LeetCode #Day13 #100DaysOfCode #Java #DSA #Arrays #ProblemSolving #CodingJourney