use sagemath built in function

src/tea3/variable_search.py

@@ -4,19 +4,10 @@ from tea3.pretty_print import pretty_print
 
 
 def count_monomials(poly):
-    s = pretty_print(poly).strip()
-    if not s or s == "0":
-        return 0
-    return sum(1 for term in s.split("+") if term.strip())
+    return len(poly.monomials())
 
 
 def apply_variable_change(model, coeffs):
-    """
-    Variable change inside each 8-bit register:
-        x_{r,0} = y_{r,0} + a1*y_{r,1} + ... + a7*y_{r,7}
-        x_{r,j} = y_{r,j} for j = 1..7
-    for every register r in {0,...,4}.
-    """
     orig_x = [list(model.v[r * 8 : (r + 1) * 8]) for r in range(5)]
     orig_y = model.y_bits