Algorithm 1: SOA

Input: Objective function f(x), seagull population size N, dimensional space D, maximum number of iterations T.

1. Initialize population; 2. Set $f_C$ to 2; 3. Set u and v to 1; 4. While t < T 5.      for i = 1 : N 6.      Calculate seagull migration position ${\overrightarrow{D}}_S$ by Equation (5); 7.      Compute $x^{\prime }$,$y^{\prime }$,$z^{\prime }$,$r$ using Equations (6)–(9); 8.      Calculate seagull attack position ${\overrightarrow{P}}_{S1}(t)$ by Equation (10); 9.      Update seagull optimal position ${\overrightarrow{P}}_{bS}(t)$; 10.      t = t + 1; 11.    end for 12. end while 13. Output the global optimal solution.