首先水平中轴翻转
然后再沿正对角线翻转

class Solution:
    def rotateMatrix(self, mat, n):
        # write code here
        # 
        for i in range(n//2):
            mat[i], mat[n-i - 1] = mat[n-i - 1], mat[i]
        for i in range(n):
            for j in range(i):
                mat[i][j], mat[j][i] = mat[j][i], mat[i][j]
        return mat