Rotating Matrix 90 Degrees Clockwise in Place

#100DaysOfLeetcode journey 🚀 Day 47/100 — Mathematical Symmetry in Matrix Rotations! Today’s Problem: 48. Rotate Image 🔹 The Goal: Rotate an $n \times n$ 2D matrix (representing an image) 90 degrees clockwise. The catch? It must be done in-place, meaning we can't allocate a second matrix to simplify the move. 🔹 The Insight: At first glance, moving every element to its new $(x, y)$ coordinate feels like a complex mapping nightmare. However, there is a beautiful geometric shortcut. A 90-degree clockwise rotation is equivalent to two simple operations: Transpose: Flip the matrix over its main diagonal. Reverse: Flip each row horizontally. 🔹 The Logic: In-Place Transpose: By swapping matrix[i][j] with matrix[j][i], we turn rows into columns. Row Reversal: Once transposed, reversing the elements in each row completes the clockwise shift. Efficiency: This approach uses $O(1)$ auxiliary space and $O(n^2)$ time, touching each element only twice. ✨ Achievement: Day 47! Successfully replaced a complex coordinate-mapping problem with a clean, two-step symmetry transformation. It’s a perfect example of how breaking a large problem into two fundamental geometric steps makes the code much more readable and easier to debug. 🔍 Steps followed: ✔ Diagonal Swapping: Implemented the transpose logic using nested loops with a j = i starting constraint. ✔ Symmetric Row Reversal: Used the two-pointer approach to flip rows in-place. ✔ Zero-Memory Footprint: Verified that no extra arrays were used, maintaining strict space efficiency. 🔧 Complexity Analysis: Time Complexity: $O(n^2)$ Space Complexity: $O(1)$ 47 days in! Sometimes the shortest path to a solution isn't a straight line—it's a flip and a reverse. 🛠️ #Java #DSA #LeetCode #CodingJourney #100DaysOfCode #SoftwareEngineer #InternshipBound #Programming #MatrixAlgorithms #Geometry #Optimization #Day47

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