*2.3. 100-Digit Challenge*

The 100-Digit Challenge problem was originally proposed by SIAM [75], which is a test method for accuracy calculation, and has been studied by many experts. Many algorithms have been applied to this challenge, and some of them are hybrid algorithms that are used to challenge this problem. Epstein et al. [76] combined the genetic algorithm (GA) with differential evolution (DE) algorithm to search the genetic space and find the latest solution. The new algorithm improved the ability to find the right answer through the fitness-based opposition and tide mutation. Brest et al. [77] used the self-adaptive differential evolution (jDE) algorithm in the DE algorithm to solve this problem, and also go<sup>t</sup> better results. Different from the above algorithms, Zhang et al. [78] proposed a new DE algorithm named collective information powered DE. This new algorithm proposed a restart mechanism through collective population information to improve the robustness.

#### **3. KH and PSO**

KH and PSO are very efficient algorithms in the field of swarm intelligence, and we will respectively introduce them in the following.
