题解 | #称砝码#

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(sc.hasNext()){
            int n = sc.nextInt();
            int[] sMs = new int[n];
            int[] sXs = new int[n];
            HashSet<Integer> set = new HashSet<>();
            //关键点就是set必须手动添加一个元素，从而进入循环，添加元素。
            set.add(0);
            // 砝码种类
            for (int i = 0; i < n; i++) {
                sMs[i] = sc.nextInt();
            }
            // 砝码个数
            for (int i = 0; i < n; i++) {
                sXs[i] = sc.nextInt();
            }
            for (int i = 0; i < n; i++) {
                ArrayList<Integer> list = new ArrayList<>(set);
                //每个砝码的个数，关键步骤，只要有砝码，至少为1个
                for (int j = 1; j <= sXs[i]; j++) {
                    for (int k = 0; k < list.size(); k++) {
                        set.add(list.get(k) + sMs[i] * j);
                    }
                }
            }
            System.out.println(set.size());
        }
    }
}