Solution:
We shall prove that Elitza has a winning strategy. If the polynomial is a0x4+a1x3+a2x2+a3x+a4 and Aleksander writes a0, a1, a2 or a3, then Elitza writes respectively a1=a0, a0=a1, a3=a2 or a2=a3; if he writes a4, she writes a1=1.
In a similar way Elitza is able to get a1≤a0 and a3≤a2 after her second move. Suppose that the polynomial obtained has an integer root −y. Then y≥1 and hence a4=y3(a1−a0y)+a3−a2y≤0, which is a contradiction.