leetcode: 48. Rotate Image

# You are given an n x n 2D matrix representing an image.
#
# Rotate the image by 90 degrees (clockwise).
#
# Note:
# 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:
#
# Given input matrix =
# [
#     [1,2,3],
#     [4,5,6],
#     [7,8,9]
# ],
#
# rotate the input matrix in-place such that it becomes:
# [
#     [7,4,1],
#     [8,5,2],
#     [9,6,3]
# ]
# Example 2:
#
# Given input matrix =
# [
#     [ 5, 1, 9,11],
#     [ 2, 4, 8,10],
#     [13, 3, 6, 7],
#     [15,14,12,16]
# ],
#
# rotate the input matrix in-place such that it becomes:
# [
#     [15,13, 2, 5],
#     [14, 3, 4, 1],
#     [12, 6, 8, 9],
#     [16, 7,10,11]
# ]

# matrix = [[1, 2, 3],
#           [4, 5, 6],
#           [7, 8, 9]]

# reverse= [[7, 8, 9],
#           [4, 5, 6],
#           [1, 2, 3]]

# output = [[7, 4, 1],
#           [8, 5, 2],
#           [9, 6, 3]]

class Solution():
    def rotate(self, matrix):
        matrix.reverse()
        for i in range(len(matrix)-1):
            for j in range(i+1, len(matrix[0])):
                matrix[i][j], matrix[j][i] = matrix[j][i], matrix[i][j]


if __name__ == "__main__":
    x = [[1, 2, 3],
         [4, 5, 6],
         [7, 8, 9]]
    Solution().rotate(x)
    assert x == [[7, 4, 1],
                 [8, 5, 2],
                 [9, 6, 3]]

class Solution():
    def rotate(self, matrix):
        for row in matrix:
            row.reverse()
        for i in range(len(matrix)-1):
            for j in range(i+1, len(matrix[0])):
                matrix[i][j], matrix[j][i] = matrix[j][i], matrix[i][j]


if __name__ == "__main__":
    x = [[1, 2, 3],
         [4, 5, 6],
         [7, 8, 9]]
    Solution().rotate(x)
    assert x == [[3, 6, 9],
                 [2, 5, 8],
                 [1, 4, 7]]