……
＞﹏＜
只给了80分
wuwuwuwuwuwuwuwwuwuwuwuwu(此处省略1万个wu）
算了，给多少算多少，附上80分代码：
听取WA声一片(￣_￣|||)

#include<bits/stdc++.h>
using namespace std;
int n,m,k;
int a[20+10];
int main(){
	freopen("shelf.in","r",stdin);
	freopen("shelf.out","w",stdout);	
    cin>>n>>k;
    for(int i=1; i<=n; i++)cin>>a[i],m+=a[i];
    sort(a+1,a+n+1);
    int f[m+1];
    f[0]=1;
    for(int i=1;i<=n;i++){ 
        for(int j=k;j>=0;j--){		
            if(f[j]==1){			
                f[j+a[i]]=1;
            }
        }
    }
    for(int i=k;i<=m;i++){
        if(f[i]==1){	
            cout<<i-k<<endl;	
            return 0;
        }
    }
    return 0;
}

正努力AC！

记录详情 - JMYSOJ (jmfes.com) 包AC的

```#include
#include <bits/stdc++.h>
using namespace std;
int n, b;
int a[30];
int minn = 1e9;

int per[15];
//u表示处理到的数字下标，sum表示已经选取的数字和
void dfs (int u, int sum){
if(sum >= b && sum <= minn){
minn = sum;
return;
}
for(int i = u; i <= n; i ++){
dfs(i + 1, sum + a[i]);
}
}

int main(){
freopen("shelf.in", "r", stdin);
freopen("shelf.out", "w", stdout);
cin >> n >> b;
for(int i = 1; i <= n; i ++){
cin >> a[i];
}
dfs(1, 0);
cout << minn - b;
return 0;
}

#include<bits/stdc++.h>
#define int long long
const int inf = 0x3f3f3f3f;
const int N = 1e6 + 1;
using namespace std;
int hqt[N];
int n , b;
int zhou = inf;
bool pei[N];
void dfs(int l,int step , int sum){
if(step > n){
return;
}
if(sum >= b){
zhou = min(zhou , sum - b);
return;
}
for(int i = l ; i <= n ; i ++){
if(pei[i]){
continue;
}
pei[i] = true;
dfs(i,step + 1 , sum + hqt[i]);
pei[i] = false;
}

}
signed main(){
freopen("shelf.in" , "r" , stdin);
freopen("shelf.out" , "w" , stdout);
cin >> n >> b;
for(int i = 1 ; i <= n ; i ++){
cin >> hqt[i];
}
dfs(1 , 0 , 0);
cout << zhou;
return 0;
}