How to select the powers of x termwise based on the results of its mod 3 in mathematica

I have a polynomial in x, for example,

x^4/s +  x^开发者_如何学JAVA3 + x^2*s + x^3*s^2 + x

What I want to do is:

based on the result of (the exponent of x) mod 3,

   if it's 0, change the x^* to 1;  
   if it's 1, change the x^* to 2;  
   if it is 2, change x^* to 3. 

So I want to get:

x^4 => 2

x^3 => 1

x^2 => 3

x^1 => 2

therefore, for the given example, I get

2/s+1+3s+s^2+2

How to do this programmably? Thanks!

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The following:

(x^4/s + x^3 + x^2*s + x^3*s^2 + x) /. x^(a : _ : 1) :> (Mod[a, 3] + 1)

seems to do it.

Edit: Answering the comment:

In[4]:= (x^4/s + x^3 + x^2*s + x^3*s^2 + x) /. 
    x^(a : _ : 1) :> (Mod[a, 3] /. {0 :> m, 1 :> n, 2 :> p})


Out[4]= m + n + n/s + p s + m s^2