题解 | #称砝码#

import java.util.HashSet;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
//        对于每组测试数据：
//        第一行：n --- 砝码的种数(范围[1,10])
//        第二行：m1 m2 m3 ... mn --- 每种砝码的重量(范围[1,2000])
//        第三行：x1 x2 x3 .... xn --- 每种砝码对应的数量(范围[1,10])
        Scanner in = new Scanner(System.in);
        while (in.hasNextLine()){
            int n = Integer.parseInt(in.nextLine());
            String[] strwight = in.nextLine().split(" ");
            String[] strnum = in.nextLine().split(" ");
            int[] wightarr = new int[n];
            int[] numarr = new int[n];
            HashSet<Integer> set = new HashSet<>();
            set.add(0);
            for (int i = 0; i < n; i++) {
                if(strwight[i] == null || strnum[i]==null){
                    continue;
                }
                wightarr[i] = Integer.parseInt(strwight[i]);
                numarr[i] = Integer.parseInt(strnum[i]);
            }
            for (int i = 0; i < n; i++) {//循环n个砝码
                HashSet<Integer> setTemp = new HashSet<>();
                for (int j = 1; j <= numarr[i]; j++) { //每个砝码可以用j个
                    setTemp.add(wightarr[i] * j);
                    for (int wight: set) {
                        setTemp.add(wight + wightarr[i] * j);//当前砝码和前面的砝码可能形成的重量组合
                    }
                }
                set.addAll(setTemp);
            }
            System.out.println(set.size());
        }

    }
}