关于此代码的时间复杂度

#include <bits/stdc++.h>
#define mod 998244353
#define ll long long
#define N 5000
#define int long long

using namespace std;

int c,t,n,m;
int a[N+2],ans;
bool vis[N+2];

int read(){
    int f=1,x=0;
    char c=getchar();
    while(c<'0' || c>'9'){if(c=='-')f=-1;c=getchar();}
    while(c>='0' && c<='9') x=x*10+c-'0',c=getchar();
    return f*x;
}

ll _pow(ll x,int y){
    ll res=1;
    while(y){
        if(y&1) res=res*x%mod;
        x=x*x%mod;
        y>>=1;
    }
    return res;
}

int f(const int &x){
    int c=m,cnt=0;
    pair<double,int> b[n+2];
    for(int i=1;i<=n;i++)   b[i]={(double)a[i]/(double)(((x>>i-1)&1)+1),i};
    sort(b+1,b+n+1);
    for(int i=n;i;i--){
        if(c-(((x>>b[i].second-1)&1)+1)<0)  continue;
        c-=(((x>>b[i].second-1)&1)+1);
        cnt+=a[b[i].second];
    }
    return cnt;
}

int dfs(int last,int c,int tot,const int &x){
    if(c<0) return tot-a[last];
    int res=tot;
    for(int i=1;i<=n;i++){
        if(!vis[i]){
            vis[i]=1;
            res=max(res,dfs(i,c-(((x>>i-1)&1)+1),tot+a[i],x));
            vis[i]=0;
        }
    }
    return res;
}

int _f(const int &x){return dfs(0,m,0,x);}

signed main(){
    freopen("sale.in","r",stdin);
    freopen("sale.out","w",stdout);
    c=read(),t=read();
    while(t--){
        ans=0;
        n=read(),m=read();
        for(int i=1;i<=n;i++)   a[i]=read();
        if(c==18 || c==16){
            printf("%lld\n",_pow(2,n));
            continue;
        }
        sort(a+1,a+n+1);
        int temp=0,c=m;
        for(int i=0;i<(1<<n);i++){
            ans+=(f(i)==_f(i));
        }
        printf("%lld\n",ans);
    }
    return 0;
}