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OJ notes/pages/Leetcode Rotate-Image.md

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+# Leetcode Rotate-Image
+
+2022-09-02 15:40
+
+> ##### Algorithms:
+> #algorithm #math
+> ##### Data structures:
+> #DS #array 
+> ##### Difficulty:
+> #coding_problem #difficulty-medium 
+> ##### Additional tags:
+> #leetcode #CS_list_need_understanding
+> ##### Revisions:
+> N/A
+
+##### Links:
+- [Link to problem](https://leetcode.com/problems/rotate-image/)
+- [Solution and explanation](https://leetcode.com/problems/rotate-image/solution/)
+___
+### Problem
+
+You are given an `n x n` 2D `matrix` representing an image, rotate the image by **90** degrees (clockwise).
+
+You have to rotate the image [**in-place**](https://en.wikipedia.org/wiki/In-place_algorithm), which means you have to modify the input 2D matrix directly. **DO NOT** allocate another 2D matrix and do the rotation.
+
+#### Examples
+
+**Example 1:**
+
+![](https://assets.leetcode.com/uploads/2020/08/28/mat1.jpg)
+
+```
+**Input:** matrix = [[1,2,3],[4,5,6],[7,8,9]]
+**Output:** [[7,4,1],[8,5,2],[9,6,3]]
+```
+
+**Example 2:**
+
+![](https://assets.leetcode.com/uploads/2020/08/28/mat2.jpg)
+
+```
+**Input:** matrix = [[5,1,9,11],[2,4,8,10],[13,3,6,7],[15,14,12,16]]
+**Output:** [[15,13,2,5],[14,3,4,1],[12,6,8,9],[16,7,10,11]]
+```
+
+#### Constraints
+
+### Thoughts
+
+> [!summary]
+> This is a #math problem.
+
+Mainly two ways
+
+#### Method 1: rotate in rings
+
+#### Method 2: transpose and reflect
+
+### Solution
+