How do you rotate a two dimensional array?

by

O(n^2) time and O(1) space algorithm ( without any workarounds and hanky-panky stuff! )

Rotate by +90:

  1. Transpose
  2. Reverse each row

Rotate by -90:

Method 1 :

  1. Transpose
  2. Reverse each column

Method 2 :

  1. Reverse each row
  2. Transpose

Rotate by +180:

Method 1: Rotate by +90 twice

Method 2: Reverse each row and then reverse each column (Transpose)

Rotate by -180:

Method 1: Rotate by -90 twice

Method 2: Reverse each column and then reverse each row

Method 3: Rotate by +180 as they are same

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