message: Update k-similar-strings.py
diff: -# Time: O(s * s!/(a!*...*z!)), s is the length of A, B,
  -# a...z is the count of each alphabet,
  -# sum(a...z) = s
  -# Space: O(s * s!/(a!*...*z!))
  +# Time: O(n * n!/(c_a!*...*c_z!), n is the length of A, B,
  +# c_a...c_z is the count of each alphabet,
  +# n = sum(c_a...c_z)
  +# Space: O(n * n!/(c_a!*...*c_z!)
  # Strings A and B are K-similar (for some non-negative integer K)
  # if we can swap the positions of two letters
  