[Leetcode/파이썬] 48. Rotate Image

Rotate Image

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You are given an n x n 2D matrix representing an image, rotate the image by 90 degrees (clockwise).

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:

Input: matrix = [[1,2,3],[4,5,6],[7,8,9]]
Output: [[7,4,1],[8,5,2],[9,6,3]]

Example 2:

Input: matrix = [[5,1,9,11],[2,4,8,10],[13,3,6,7],[15,14,12,16]]
Output: [[15,13,2,5],[14,3,4,1],[12,6,8,9],[16,7,10,11]]

 

Constraints:

• n == matrix.length == matrix[i].length
• 1 <= n <= 20
• -1000 <= matrix[i][j] <= 1000

 

class Solution:
    def rotate(self, matrix: List[List[int]]) -> None:
        """
        Do not return anything, modify matrix in-place instead.
        """
        n = len(matrix)
        
        top = 0
        bottom = n - 1

        while top < bottom :
            for col in range(n) :
                tmp = matrix[top][col]
                matrix[top][col] = matrix[bottom][col]
                matrix[bottom][col] = tmp
            top += 1
            bottom -= 1
    
        for row in range(n) :
            for col in range(row+1, n) :
                tmp = matrix[row][col]
                matrix[row][col] = matrix[col][row]
                matrix[col][row] = tmp

 

class Solution:
    def rotate(self, matrix: List[List[int]]) -> None:
        """
        Do not return anything, modify matrix in-place instead.
        """
        
        n = len(matrix)
        for i in range(n) :
            for j in range(i + 1, n) :
                matrix[i][j], matrix[j][i] = matrix[j][i], matrix[i][j]

        for i in range(n) :
            matrix[i].reverse()