#48 Rotate Image

class Solution:
    def rotate(self, matrix: List[List[int]]) -> None:
        """
        Do not return anything, modify matrix in-place instead.
        """
        n = len(matrix) - 1
        a, b = 0, 0
        count = 0
        while n >= 1:
            count += 1
            con = []
            for _ in range(n):
                con.append(matrix[a][b])
                b += 1
            for _ in range(n):
                con.append(matrix[a][b])
                matrix[a][b] = con[0]
                del con[0]
                a += 1
            for _ in range(n):
                con.append(matrix[a][b])
                matrix[a][b] = con[0]
                del con[0]
                b -= 1
            for _ in range(n):
                con.append(matrix[a][b])
                matrix[a][b] = con[0]
                del con[0]
                a -= 1
            for _ in range(n):
                matrix[a][b] = con[0]
                del con[0]
                b += 1
            a, b = count, count
            #print(matrix, n, count)
            n -= 2


## Initially transpose, (전치행렬) then flip horizontally, (discussion forum ans)
class Solution(object):
    def rotate(self, matrix):
        n = len(matrix)
        # transpose
        for i in range(n):
            for j in range(i + 1, n):
                tmp = matrix[i][j]
                matrix[i][j] = matrix[j][i]
                matrix[j][i] = tmp
        # flip horizontally
        for i in range(n):
            for j in range(n/2):
                tmp = matrix[i][j]
                matrix[i][j] = matrix[i][n - 1 - j]
                matrix[i][n - 1- j] = tmp