题解 | 装箱问题

import java.util.Scanner;
import java.util.*;
// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextInt()) { // 注意 while 处理多个 case
            int a = in.nextInt();
            int b = in.nextInt();
  
            int[] data = new int[b];
            int total = 0;
            for (int i = 0; i < b; i++) {
                data[i] = in.nextInt();
                 total = total + data[i];
            }
           if (total <= a) {
                System.out.println(a - total);
            }else {
                minValue = a;
                computeData(minValue,data,new boolean[data.length]);
                System.out.println(minValue);
            }
        }
    }
    public static int minValue = 0;
    public static boolean  computeData(int total, int[] data, boolean[] da) {
        minValue = Math.min(total, minValue);
        if (total == 0) {
            return true;
        }
        for (int i = 0; i < data.length; i++) {
            if (da[i]) {
                continue;
            }

            if (data[i] <= total) {
                da[i] = true;
                boolean b = computeData(total - data[i], data, da);
                if (b) {
                    return true;
                }
                da[i] = false;
            }
        }
        return false;
    }
}