Algorithm 1 The framework of CASSA

/*Initialization*/ 1. Set the maximum iterations as $T_{\max }$; 2. Set the number of finders as $F_d$; 3. Set the number of threatened sparrows as $S_d$; 4. Set the alarm value as $G$; 5. Set the number of sparrows as $n$; 6. Initialize the position of n sparrows using Equation (5); /*Iterative search*/ 7. while ($t<T_{\max }$) 8. Rank the fitness values and find the best individual and the worst individual currently; 9.  $G=rand(1)$; 10. for $i=1:F_d$ 11.   Update the finder’s position using Equation (7); 12. end for 13. for $i=(F_d+1):n$ 14.   Update the entrant’s position using Equation (3); 15. end for 16. for $i=1:S_d$ 17.   Update the threatened sparrow’s position using Equation (4); 18. end for 19. Select the top S elite individuals and implement adaptive mutation for them by Equation (9); 20. Get the current new position; 21. If the new position is better than before, update it; 22. $t=t+1$; 23. end while 24. Output the best solution