java ：动态规划

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        HashMap<Integer,Boolean> hash = new HashMap<>();
        int n = sc.nextInt(), sum = sc.nextInt();
        int[] W = new int[n];
        for(int i = 0; i < n; i++){
            W[i] = sc.nextInt();
        }
        int[] dp = new int[sum+1];
        dp[0] = 1;
        for (int Wi : W){
            for (int i = 0; i + Wi <= sum; i++) {
                dp[i+Wi] = dp[i+Wi]+dp[i];
            }
        }
        System.out.println(dp[sum]);
    }
}