方阵的旋转？ [英] rotatiion of a square matrix?

问题描述

如何使用O（1）额外空格将方阵旋转90度????

解决方案

将矩阵视为一组嵌套正方形。您可以单独旋转每个方块。要将方块旋转N个位置，可以将其旋转N次一个位置。要旋转一个位置，将一个元素保存到额外的存储空间，循环移动其他元素并放回已保存的元素。

 ABCDE 
 PF 
 OG 
 NH 
 MLKJI 
 
  -  BCDEA 
 PF 
 OG 
 NH 
 MLKJI 
 
 BCDE -  A 
 PF 
 OG 
 NH 
 MLKJI 
 
 BCDEFA 
 PG 
 OH 
 NI 
 MLKJ  -  
 
 BCDEFA 
 PG 
 OH 
 NI 
  -  MLKJ 
 
 BCDEFA 
  -  G 
 PH 
 OI 
 NMLKJ 
 
 BCDEF 
 AG 
 PH 
 OI 
 NMLKJ 

how to rotate a square matrix by 90degrees with O(1) extra space????

解决方案

See the matrix as a set of nested squares. You can rotate each square independently. To rotate a square by N positions, you can rotate it N times by one position. To rotate by one position, save one element to extra storage, shift the others circularly and put back the saved element.

A B C D E
P       F
O       G
N       H
M L K J I

- B C D E     A
P       F
O       G
N       H
M L K J I

B C D E -     A
P       F
O       G
N       H
M L K J I

B C D E F     A
P       G
O       H
N       I
M L K J -

B C D E F     A
P       G
O       H
N       I
- M L K J

B C D E F     A
-       G
P       H
O       I
N M L K J

B C D E F
A       G
P       H
O       I
N M L K J

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