g0001_0100.s0048_rotate_image.readme.md Maven / Gradle / Ivy

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48\. Rotate Image

Medium

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.

**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:** \[\[15,13,2,5\],\[14,3,4,1\],\[12,6,8,9\],\[16,7,10,11\]\] 

**Example 3:**

**Input:** matrix = \[\[1\]\]

**Output:** \[\[1\]\] 

**Example 4:**

**Input:** matrix = \[\[1,2\],\[3,4\]\]

**Output:** \[\[3,1\],\[4,2\]\] 

**Constraints:**

*   `matrix.length == n`
*   `matrix[i].length == n`
*   `1 <= n <= 20`
*   `-1000 <= matrix[i][j] <= 1000`