Sample Input 1: 3 1 2 3 4 5 6 7 8 9 Sample Output 1: 7 2 9 4 5 6 1 8 3

def rotate_matrix(matrix):
    m = len(matrix)
    n = len(matrix[0])
    ret = [[0]*m for _ in range(n)] 
    for i in range(m):
        for j in range(n):
            ret[j][m-1-i] = matrix[i][j]
    return ret