算法训练 装箱问题

 1 import java.math.BigInteger;
 2 import java.util.Arrays;
 3 import java.util.Scanner;
 4 
 5 
 6 public class Main {
 7     static int n;
 8     static int[] a;
 9     static int mix = 200000;
10     public static void main(String[] args) {
11         Scanner input = new Scanner(System.in);
12         int sum = input.nextInt();
13         n = input.nextInt();
14         a = new int[n];
15         for(int i=0;i<n;i++){
16             a[i] = input.nextInt();
17         }
18         f(sum,0);
19         System.out.println(mix);
20                 
21     }
22     public static int f(int sum,int i){
23         if(sum<0) return -1;
24         if(i==n) {if(mix>sum)    mix = sum;}
25             for(int j=i;j<n;j++){
26                 if(f(sum-a[j],j+1)==-1){
27                     if(mix>sum)    mix = sum;
28                 }
29             }
30             return sum;
31         
32         
33         
34 
35     }
36 }