Rotate matrix lcci
class Solution:
def rotate(self, matrix: List[List[int]]) -> None:
"""
Do not return anything, modify matrix in-place instead.
"""
# stretegy: horizental flip then diagonal flip
# horitzental flip first:
n = len(matrix)
for i in range(n//2):
for j in range(n):
matrix[i][j],matrix[n-1-i][j] = matrix[n-1-i][j],matrix[i][j]
# diagonal flip
for i in range(n):
for j in range(i):
matrix[i][j],matrix[j][i] = matrix[j][i],matrix[i][j]