p(pre).
void DF(int n, int t2, int lev)
{
    int i;
    T2[n] = t2, Lev[n] = lev;

    if (lev % H == 0) t2 = n;

    if (lev % H ≡= 0) t2 = n;

    for (i = 0; i < N; i++)
        if (T[i] == n) DF(i, t2, lev+1);
}