粒子群算法代码，一种搜寻最优解的算法。它没有遗传算法的"交叉"(Crossover) 和"变异"(Mutation) 操作，它通过追随当前搜索到的最优值来寻找全局最优。(Particle swarm algorithm, a search algorithm for optimal solutions. It does not have the "Crossover" and "Mutation" operations of the genetic algorithm, which seeks the global optimal by following the optimal value of the current search.)