那么。。蒟蒻我只好求助各位大佬了

#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
int lowbit(int x)
{
    return x&-x;
}
int n,a[100010],c[100010],pos[100010],ans,out[100010],cnt;
void add(int x,int delta)
{
    for (int i=x;i<=2*n;i+=lowbit(i))
    {
        c[i]+=delta;
    }
}
int query(int x)
{
    int re=0;
    for (int i=x;i;i-=lowbit(i))
    {
        re+=c[i];
    }
    return re;
}
int main()
{
    //freopen("tet.in","r",stdin);
    //freopen("tet.out","w",stdout);
    scanf("%d",&n);
    for (int i=1;i<=2*n;i++)
    {
        scanf("%d",&a[i]);
    }
    for (int i=1;i<=2*n;i++)
    {
        if (pos[a[i]]==0)
        {
            pos[a[i]]=i;
            add(i,1);
        }
        else
        {
            int delta=query(i)-query(pos[a[i]]);
            add(pos[a[i]],-1);
            ans+=delta;
            if (delta>0) out[++cnt]=2*n-i+1;
            pos[a[i]]=0;
        }
    }
    printf("%d\n",ans);
    for (int i=1;i<=cnt-1;i++)
    {
        printf("%d\n",out[i]);
    }
    printf("%d",out[cnt]);
    return 0;
}