Algorithm 1: CH Selection Based on BWOA

Input:${UAV}_i$, i = 1, 2, …, N.

Output: Cluster head ${CH}_j$, j = 1, 2, …, K.

/* Initialization phase*/

$1: \mathrm{Initialize} \mathrm{the} \mathrm{whale} \mathrm{population} X=[X1,X2,\dots ,XN]$.

$2: \mathrm{Initialize} \mathrm{iteration} t=1, \mathrm{maximum} \mathrm{number} \mathrm{of} \mathrm{iterations} t\max$.

3: Calculate the fitness of each whale.

$4: \mathrm{Choose} \mathrm{the} \mathrm{best} \mathrm{solutions} X^{*}(t)$

/* Computation*/

5: while $(t<t_{\max }$), do

6:     for each search agent, do

7:         Update A, C and a by (10)–(12).

8:         if p < 0.5 then

9:            if $\left|A\right|<1$ then

$10: \mathrm{Update} D_1$$\mathrm{by} \left(8\right) \mathrm{and} {\gamma }_1$ by (17).

11:               Update the position X based on (18).

12:            else

$13: \mathrm{Select} \mathrm{a} \mathrm{random} X_{rand}$$\mathrm{and} \mathrm{update} D_3$ by (15) and (16).

$14: \mathrm{Update} {\gamma }_3$ by (21) and the position X by (22).

15:           end if

16:        else

$17: \mathrm{Update} D2$$\mathrm{by} \left(14\right) \mathrm{and} \gamma 2$ by (19).

18:            Update the position X by (20).

19:        end if

20:     end for

21:     Calculate the fitness of each search agent by (39).

$22: \mathrm{Update} X^{*}(t)$ of the best search agent.

23:     t = t + 1

24: end while

25: return CHs