Algorithm 2 Top–Down Approach (TD)

1:Input: $\mathcal{V}$, $\mathcal{C}$, $\mathcal{L}$, $l_{min}$, $n_{max}$ 2:Output: ${\mathcal{V}}_{con}$ 3:$\mathcal{M}\leftarrow$ Select all $v_i,c_j\in \{\mathcal{L}$|$l_{v_i,c_j}\ge l_{min}\}$ 4:$\mathcal{Q}\leftarrow$ Select distinct $c_j$ from $\mathcal{M}$ 5: ${\mathcal{V}}_{con}\leftarrow \left\{\right\}$ 6:while True do 7:    $\mathcal{K}\leftarrow$ Select all $c_j,(count\left(v_i\right)$ as $n_v)\in \{\mathcal{M}$|$n_{v_z}>n_{v_{z+1}}\}$ 8:    if $\mathcal{K}\ne \left\{\right\}$ then 9:        $s_i\leftarrow$$\{k_1$|$k_1$ is the first $c_j$ of $\mathcal{K}\}$ 10:        $\mathcal{N}\leftarrow$ Select ${(v_i,c_j)}_n\in \{\mathcal{M}$|$(c_j=s_i)\wedge (n\in \{1,2,..,n_{max}\})\wedge (dist(v_i,c_j)\le s_i^r)\wedge ({\left(l_{v_i,c_j}\right)}_z$>${\left(l_{v_i,c_j}\right)}_{z+1}\left)\right\}$ 11:        $\mathcal{M}\leftarrow \mathcal{M}-\mathcal{N}$ 12:        $\mathcal{Q}\leftarrow \mathcal{Q}-\left\{s_i\right\}$ 13:        ${\mathcal{V}}_{con}\leftarrow {\mathcal{V}}_{con}\cup \{<v_i,s_i,l_{v_i,s_i}>\forall v_i\in \mathcal{N}\}$ 14:    else 15:        exit 16:    end if 17:    if $\mathcal{Q}=\left\{\right\}$ then 18:        exit 19:    end if 20: end while