Rutik Jaybhaye’s Post

Day 48 of Daily DSA 🚀 Solved LeetCode 48: Rotate Image ✅ Problem: Given an n x n matrix, rotate the image by 90° clockwise — in-place (without using extra space). Approach: Used a two-step transformation: Transpose the matrix Reverse each row Steps: Traverse upper triangle and swap → matrix[i][j] ↔ matrix[j][i] For each row: Use two pointers (left, right) Swap elements to reverse the row Matrix gets rotated in-place ⏱ Complexity: • Time: O(n²) • Space: O(1) 📊 LeetCode Stats: • Runtime: 0 ms (Beats 100%) ⚡ • Memory: 43.56 MB In-place transformations are powerful — no extra space, just smart manipulation 💡 #DSA #LeetCode #Java #Matrix #Arrays #CodingJourney #ProblemSolving

75 Days of DSA – Day 2 Solved: Trapping Rain Water Approach: Two Pointers Time: O(n) | Space: O(1) Implemented an optimized solution by maintaining leftMax and rightMax to eliminate extra space and achieve linear time complexity. 324 / 324 test cases passed Runtime: 0 ms (100th percentile) Focused on improving problem-solving depth and writing optimal solutions consistently. #DSA #Algorithms #Java #ProblemSolving

Day 63/75 — Rotate Array Today’s problem was about rotating an array to the right by k steps. Approach: • Use reversal algorithm for optimal in-place rotation • Reverse entire array • Reverse first k elements • Reverse remaining elements Key logic: k = k % n; reverse(nums, 0, n - 1); reverse(nums, 0, k - 1); reverse(nums, k, n - 1); Time Complexity: O(n) Space Complexity: O(1) A classic array problem that reinforces in-place manipulation techniques. 63/75 🚀 #Day63 #DSA #Arrays #InPlace #Java #Algorithms #LeetCode

Day 56/100 | #100DaysOfDSA 🧠⚡ Today’s problem: String Compression A clean in-place array manipulation problem. Core idea: Compress consecutive repeating characters and store the result in the same array. Approach: • Traverse the array using a pointer • Count consecutive occurrences of each character • Write the character to the array • If count > 1 → write its digits one by one • Move forward and repeat Key insight: We don’t need extra space — just carefully manage read & write pointers. Time Complexity: O(n) Space Complexity: O(1) Big takeaway: In-place algorithms require precise pointer control but give optimal space efficiency. Mastering these improves real-world memory optimization skills. 🔥 Day 56 done. #100DaysOfCode #LeetCode #DSA #Algorithms #Strings #TwoPointers #InPlace #Java #CodingJourney #ProblemSolving #InterviewPrep #TechCommunity

Day 49/75 — Rearrange Array Elements by Sign Today’s problem focused on rearranging an array such that positive and negative numbers alternate, while preserving their original order. Approach: • Use two pointers (even index for positive, odd index for negative) • Traverse the array once • Place elements in correct positions directly Key logic: if (num >= 0) { result[posIdx] = num; posIdx += 2; } else { result[negIdx] = num; negIdx += 2; } Time Complexity: O(n) Space Complexity: O(n) A clean problem that reinforces index placement and pattern-based traversal. 49/75 🚀 #Day49 #DSA #Arrays #Java #Algorithms #LeetCode

Day 12 of #100DaysOfCode — Sliding Window Today, I worked on the problem “Max Consecutive Ones III” LeetCode. Problem Summary Given a binary array, the goal is to find the maximum number of consecutive 1s if you can flip at most k zeros. Approach At first glance, this problem looks like a brute-force or restart-based problem, but the optimal solution lies in the Sliding Window technique. The key idea is to maintain a window [i, j] such that: The number of zeros in the window does not exceed k Expand the window by moving j Shrink the window by moving i whenever the constraint is violated Instead of restarting the window when the condition breaks, we dynamically adjust it. Key Logic Traverse the array using pointer j Count the number of zeros in the current window If zeros exceed k, move pointer i forward until the window becomes valid again At every step, update the maximum window size Why This Works This approach ensures: Each element is processed at most twice Time Complexity: O(n) Space Complexity: O(1) The most important learning here is understanding how to dynamically adjust the window instead of resetting it, which is a common mistake while applying sliding window techniques. In sliding window problems, always focus on expanding and shrinking the window efficiently rather than restarting the computation. #100DaysOfCode #DSA #SlidingWindow #LeetCode #Java #ProblemSolving #CodingJourney #DataStructures #Algorithms

Day 46/75 — Frequency of the Most Frequent Element Today’s problem was about maximizing the frequency of an element using at most k increments. Approach: • Sort the array • Use sliding window • Maintain sum of current window • Expand right pointer • Shrink window when operations exceed k Key logic: while ((long) nums[right] * (right - left + 1) - total > k) {  total -= nums[left];  left++; } maxFreq = Math.max(maxFreq, right - left + 1); Time Complexity: O(n log n) (sorting) Space Complexity: O(1) Key Insight: Make all elements in window equal to the largest element — check if cost ≤ k. 46/75 🚀 #Day46 #DSA #SlidingWindow #TwoPointers #Java #Algorithms #LeetCode

🔥 Day 364 – Daily DSA Challenge! 🔥 Problem: 🎯 Find K Closest Elements Given a sorted array arr, an integer k, and a target x, return the k closest elements to x in ascending order. 💡 Key Insight — Binary Search on Window Instead of checking each element, we binary search the starting index of a window of size k. Search space: Possible windows → [0 ... n - k] 🧠 Decision Logic At index mid, compare: Distance of left boundary → x - arr[mid] Distance of right boundary → arr[mid + k] - x We choose direction based on: ⚡ Algorithm Steps ✅ Initialize: left = 0, right = n - k ✅ Binary search: If left side is farther → shift right Else → move left ✅ Final window starts at left ✅ Collect k elements ⚙️ Complexity ✅ Time Complexity: O(log(n - k) + k) (binary search + result building) ✅ Space Complexity: O(k) 💬 Challenge for you 1️⃣ Why do we search on window positions instead of elements? 2️⃣ Can you solve this using a heap approach? 3️⃣ What if array was unsorted? #DSA #Day364 #LeetCode #BinarySearch #SlidingWindow #Arrays #Java #ProblemSolving #KeepCoding

Day 48/75 — Max Consecutive Ones III Today’s problem was about finding the maximum consecutive 1s after flipping at most k zeros. Approach: • Use sliding window • Expand right pointer • Count zeros in window • Shrink window when zeros > k Key logic: if (nums[right] == 0) zeroCount++; while (zeroCount > k) {  if (nums[left] == 0) zeroCount--;  left++; } maxLength = Math.max(maxLength, right - left + 1); Time Complexity: O(n) Space Complexity: O(1) Key Insight: Keep the window valid by ensuring at most k zeros, and maximize its size. 48/75 🚀 #Day48 #DSA #SlidingWindow #TwoPointers #Java #Algorithms #LeetCode

Day 47 of Daily DSA 🚀 Solved LeetCode 74: Search a 2D Matrix ✅ Problem: Given a sorted 2D matrix where: • Each row is sorted • First element of each row > last element of previous row Find whether a target exists in the matrix. Approach: Used an optimized staircase search (top-right traversal). Steps: Start from top-right corner If element == target → return true If element > target → move left If element < target → move down Continue until found or out of bounds ⏱ Complexity: • Time: O(n + m) • Space: O(1) 📊 LeetCode Stats: • Runtime: 0 ms (Beats 100%) ⚡ • Memory: 43.84 MB Sometimes choosing the right starting point (top-right) makes the search super efficient 💡 #DSA #LeetCode #Java #Matrix #BinarySearch #CodingJourney #ProblemSolving