【leetcode】48. Rotate image

For details, please refer to 48. Rotated image

Their thinking ：

• Rotate the image in place , You cannot use another matrix to rotate the image
• First flip the image horizontally , The first line and the last line exchange , The second line and the last line exchange , By analogy
• Next flip diagonally

class Solution:
    def rotate(self, matrix: List[List[int]]) -> None:
        """ Do not return anything, modify matrix in-place instead. """
        #  Rotate the image in place 90 degree , Do not use another matrix to rotate the image 
        #  Double pointer 
        n = len(matrix)

        #  Flip horizontal 
        for i in range(n): # 0
            left, right =0, n-1
            while left <= right:
                matrix[left][i], matrix[right][i] = matrix[right][i], matrix[left][i]
                left += 1
                right -= 1
        #  Turn diagonally 
        for i in range(n):
            for j in range(i):
                matrix[i][j], matrix[j][i] = matrix[j][i], matrix[i][j]
        

Diagonal flip code ！！！

        for i in range(n):
            for j in range(i):
                matrix[i][j], matrix[j][i] = matrix[j][i], matrix[i][j]