Valid Word Java LeetCode Solution

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

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 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

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 66 of #100DaysOfLeetCode 💻✅ Solved #3427. Sum of Variable Length Subarrays problem in Java. Approach: • Iterated through each index of the array • Determined the starting index using i - nums[i] • Ensured the start index does not go below 0 • Calculated sum of elements from start to current index i • Added each subarray sum to the total Performance: ✓ Runtime: 1 ms (Beats 99.90% submissions) ✓ Memory: 45.22 MB (Beats 56.30% submissions) Key Learning: ✓ Practiced handling variable-length subarrays ✓ Improved understanding of index-based range calculations ✓ Strengthened nested loop logic for array problems Learning one problem every single day 🚀 #Java #LeetCode #DSA #Arrays #PrefixSum #ProblemSolving #CodingJourney #100DaysOfCode

🚀 Day 57 of My Java DSA Journey Today I worked on a classic Dynamic Programming problem: 💡 Subset Sum Problem 🧠 Approach: • Used recursion with memoization • At each step, decided whether to include or exclude an element • Stored intermediate results to optimize performance 🔍 Key Insight: A subset with sum k exists if: We can form k without current element OR We can form k - arr[i] including current element ⚡ What I learned: • DP pattern similar to Knapsack • Importance of proper memoization • Handling boolean DP states 🔥 Complexity: • Time: O(n × k) • Space: O(n × k) 🎯 Takeaway: Many DP problems are variations of a few core patterns. #Day57 #90DaysOfCoding #DSA #DynamicProgramming #Java

🚀 Java DSA Progress Update I’ve solved 125/310 problems (~40%) as part of my structured Java DSA roadmap. ✔️ Strong in: Arrays, Strings, Linked Lists, Binary Search ⚡ Focusing next on: Heap, Graphs, Dynamic Programming, Sliding Window 📌 Approach: Pattern-based problem solving Time & space analysis Learning from mistakes Re-solving for retention 🎯 Goal: Become interview-ready in 30 days with strong problem-solving fundamentals. Consistent progress > perfection. #Java #DSA #LeetCode #ProblemSolving #SoftwareEngineering

Day 65 of #100DaysOfLeetCode 💻✅ Solved “Majority Frequency Group” problem in Java. Approach: • Created a frequency array of size 26 for all characters • Counted occurrences of each character in the string • For each unique frequency, counted how many characters share that frequency • Selected the frequency with the highest group size • In case of tie, chose the higher frequency • Built the result string with characters having the selected frequency Performance: ✓ Runtime: 5 ms (Beats 57.84% submissions) ✓ Memory: 44.51 MB (Beats 72.88% submissions) Key Learning: ✓ Practiced frequency grouping techniques ✓ Learned how to handle tie-breaking conditions ✓ Strengthened logic building with nested loops and conditions Learning one problem every single day 🚀 #Java #LeetCode #DSA #Strings #Hashing #ProblemSolving #CodingJourney #100DaysOfCode

Day 84 of #100DaysOfLeetCode 💻✅ Solved #567. Permutation in String problem in Java. Approach: * Used Sliding Window with frequency array * Decreased count for incoming characters * Adjusted window when count became invalid * Checked window size equal to s1 length Performance: ✓ Runtime: 6 ms (Beats 87.55% submissions) 🚀 ✓ Memory: 43.26 MB (Beats 99.80% submissions) Key Learning: ✓ Strengthened Sliding Window with frequency tracking ✓ Learned efficient permutation checking ✓ Improved handling of dynamic window adjustment Learning one problem every single day 🚀 #Java #LeetCode #DSA #SlidingWindow #Strings #Arrays #ProblemSolving #CodingJourney #100DaysOfCode

Day 37 of My Java DSA Journey✨ Today I focused on improving my logic building skills and practiced problems using: 💡 Nested If-Else Conditions • Solved problems that required multiple condition checks • Learned how to structure logic clearly without confusion 🔄 Array Rotation • Understood how elements shift positions in an array • Practiced rotating arrays and tracking index changes 🔍 What I learned today: • Breaking complex conditions into smaller steps • Writing clean and readable logic • Importance of index handling in arrays ⚡ These problems may look simple, but they are essential for building strong problem-solving skills. 🎯 Takeaway: Strong logic + array basics = foundation for advanced DSA #Day36 #90DaysOfCoding #Java #DSA #Arrays #ProblemSolving #CodingJourney #Consistency