message: Update k-similar-strings.cpp
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!)
  +
  class Solution {
  public:
  