Majority Element LeetCode Challenge Java Solution

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

100 Days of Coding Challenge – Day 24 📌 Problem: Two Sum II – Input Array Is Sorted 💻 Language: Java 🧠 Concept Used: Two Pointer Technique 🔍 Platform: LeetCode Today’s challenge was to find two numbers in a sorted array that add up to a given target and return their 1-indexed positions. The problem guarantees exactly one valid solution and requires constant extra space. Example: Input: numbers = [2,7,11,15], target = 9 Output: [1,2] Approach: ✔ Use two pointers — one at the start (left) and one at the end (right) ✔ Calculate the sum of both elements ✔ If the sum equals the target → return their indices ✔ If the sum is smaller → move left forward ✔ If the sum is larger → move right backward Time Complexity: O(n) Space Complexity: O(1) 🔗 Problem Link: https://lnkd.in/gcM_dBA7 🔗 Code: https://lnkd.in/gaUrS-Ne #100DaysOfCode #Day24 #Java #DSA #LeetCode #TwoPointers #Arrays #ProblemSolving #CodingJourney

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 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 85 - LeetCode Journey Solved LeetCode 1721: Swapping Nodes in a Linked List in Java ✅ This problem looks tricky at first, but the idea becomes simple once you break it down. Instead of swapping nodes directly (which can get messy in linked lists), I swapped the values of the nodes. First, I moved to the k-th node from the start. Then using a second pointer and a fast pointer, I found the k-th node from the end in a single pass. Clean approach, no extra space, and efficient traversal. Key takeaways: • Smart use of two-pointer technique • Avoiding complex pointer manipulation by swapping values • Single pass solution after locating first node • Strong grip on linked list traversal ✅ All test cases passed ⚡ Optimized and clean implementation Problems like this really improve your confidence in linked lists 💯 #LeetCode #DSA #Java #LinkedList #TwoPointers #CodingJourney #ProblemSolving #InterviewPrep #Consistency #100DaysOfCode

🚀 Day 7 / 100 – LeetCode Challenge Today I solved Length of Last Word (LeetCode #58) using Java. 🔹 Problem: Given a string "s" containing words and spaces, return the length of the last word in the string. 📌 Approach: - Traverse the string from the end. - Ignore trailing spaces. - Start counting characters of the last word. - Stop when a space appears after counting begins. 💡 Key Concepts Practiced: - String traversal - "charAt()" usage - Reverse iteration - Conditional logic ⏱ Time Complexity: O(n) 📦 Space Complexity: O(1) ✅ Key Takeaway: Sometimes solving a problem becomes easier when we traverse the data from the end instead of the beginning. #100DaysOfCode #LeetCode #Java #DSA #ProblemSolving #CodingJourney

🚀 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

Solved LeetCode 17 – Letter Combinations of a Phone Number using backtracking in Java. Approach: Mapped each digit (2–9) to its corresponding characters using a simple array for O(1) access. Then used backtracking to build combinations digit by digit. For every digit: Pick each possible character Append → explore next digit → backtrack Key idea: Treat it like a tree of choices, where each level represents a digit and branches represent possible letters. Key learnings: Backtracking = build → explore → undo StringBuilder helps avoid unnecessary string creation Problems like this are about systematic exploration of choices Time Complexity: O(4^n * n) Space Complexity: O(n) recursion stack + output Consistent DSA practice is strengthening pattern recognition day by day. #Java #DSA #Backtracking #LeetCode #CodingInterview #SoftwareEngineering

Day 94 - LeetCode Journey Solved LeetCode 35: Search Insert Position in Java ✅ Classic Binary Search problem that tests your fundamentals. Instead of just finding the element, the twist is to return the correct insert position if it’s not present. The key idea is simple: keep narrowing the search space and finally return low, which represents the right position. Clean logic, high impact 💡 Key takeaways: • Strong grip on Binary Search fundamentals • Understanding search space boundaries • Returning correct insertion index • Writing efficient O(log n) solutions ✅ All test cases passed ⚡ O(log n) time and O(1) space Mastering basics like Binary Search is what builds real problem-solving strength 🔥 #LeetCode #DSA #Java #BinarySearch #ProblemSolving #CodingJourney #InterviewPrep #Consistency #100DaysOfCode

🚀 Day 57/180 | #180DaysOfCode 📍 LeetCode | 💻 Java Solved: 242. Valid Anagram Used a HashMap frequency counting approach (Unicode-safe using code points) to compare character frequencies of both strings. ⏱️ Time Complexity: O(n) 📦 Space Complexity: O(n) Strengthening understanding of string frequency analysis and Unicode handling. 💪 Consistency continues 🚀 #DSA #LeetCode #Java #CodingJourney #Consistency