# 48. Rotate Image

## 28 Dec 48. Rotate Image

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, which means you have to modify the input 2D matrix directly. DO NOT allocate another 2D matrix and do the rotation.

Example 1:

```Input: matrix = [[1,2,3],[4,5,6],[7,8,9]]
Output: [[7,4,1],[8,5,2],[9,6,3]]
```

Example 2:

```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:

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

class Solution:
def rotate(self, matrix: List[List[int]]) -> None:
“””
Do not return anything, modify matrix in-place instead.
“””
upper = 0
lower = len(matrix) – 1
while upper < lower:
temp = matrix[upper]
matrix[upper] = matrix[lower]
matrix[lower] = temp
lower = lower – 1
upper = upper + 1
print(matrix)
for i in range(len(matrix)):
for j in range(i):
temp = matrix[i][j]
matrix[i][j] = matrix[j][i]
matrix[j][i] = temp
print(matrix)