10pts求助

#include<bits/stdc++.h>
using namespace std;
const int N=2e6+9;
long long n,m,a[N],b[N],cnta,cntb,numa[N],numb[N],suma,sumb,ans;
void dfs(long long x,long long y){
    //cout<<x<<" "<<y<<endl;
    if(y>m)return;
    if(x==cnta+1){
        numa[++suma]=y;
        return;
    }
    //cout<<a[x]<<endl;
    dfs(x+1,y+a[x]);
    dfs(x+1,y);
}
void dfs2(long long x,long long y){
    if(y>m)return;
    if(x==cntb+1){
        //cout<<x<<" "<<y<<endl;
        numb[++sumb]=y;
        return;
    }
    dfs2(x+1,y+b[x]);
    dfs2(x+1,y);
}
int main(){
    scanf("%lld%lld",&n,&m);
    for(int i=1;i<=n;i++){
        long long x;
        scanf("%lld",&x);
        if(i<=n/2)a[++cnta]=x;
            else b[++cntb]=x;
    }
//  for(int i=1;i<=cnta;i++)cout<<a[i]<<" ";
//  cout<<endl;
    dfs(1,0);
    dfs2(1,0);
    sort(numa+1,numa+cnta+1);
    //for(int i=1;i<=suma;i++)cout<<a[i]<<" ";
    //cout<<endl;
    for(int i=1;i<=sumb;i++)
        ans+=upper_bound(numa+1,numa+suma+1,m-numb[i])-numa-1;
    printf("%lld",ans);
    return 0;
}