题解 | #称砝码#

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String[] args) {
        BufferedReader r = new BufferedReader(new InputStreamReader(System.in));
        String a, b, c;
        try {
            a = r.readLine();
            b = r.readLine();
            c = r.readLine();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        int i = 0, j, k, n = 0, l, tol = 0, weight = 0, t, ans = 0;
        char[] ch1 = a.toCharArray();
        l = ch1.length;
        do {
            n *= 10;
            n += ch1[i] - '0';
            i++;
        } while (i < l);
        int[] wt = new int[n];
        int[] ct = new int[n];
        char[] ch2 = b.toCharArray();
        char[] ch3 = c.toCharArray();
        parsing(ch2, wt);//获得每一种砝码的重量
        parsing(ch3, ct);//获得每一种砝码的数量
        i = 0;
        do {//遍历计算总重量
            tol += wt[i] * ct[i];
            i++;
        } while (i < n);
        int[] mark = new int[tol + 1];
        mark[0] = 1;//称重重量0包含，置为1
        i = 0;
        do {//遍历种类
            l = ct[i];
            j = 0;
            do {//遍历每种的数量
                weight += wt[i];//当前砝码加入称重时的最大重量
                mark[weight] = 1;//当前砝码都加入时的总重量，置为1
                k = weight - 1;
                do {//逆序遍历，有1，加上当前砝码重量，可称重量置为1
                    if (mark[k] == 1) {
                        t = k + wt[i];
                        mark[t] = 1;
                    }
                    k--;
                } while (k > -1);
                j++;
            } while (j < l);
            i++;
        } while (i < n);
        i = 0;
        do {//数组元素为1，表示该下标重量可称
            if (mark[i] == 1) ans++;
            i++;
        } while (i < tol + 1);
        System.out.print(ans);
    }

    //获得重量和数量
    public static void parsing(char[] chs, int[] arr) {
        int j = 0, k = 0, num = 0;
        int l = chs.length;
        do {
            if (chs[j] == ' ') {
                arr[k++] = num;
                num = 0;
                j++;
                continue;
            }
            num *= 10;
            num += chs[j] - '0';
            if (j == l - 1) arr[k] = num;
            j++;
        } while (j < l);
    }
}