警示后人：如果你一直20分

这是本蒟蒻写代码时的所有bug，调了一个晚上，发出来希望能够帮到大家

问题全在注释里了

int n,q,B;
int a[N],b[N];
int idx[N],pos[N];
int t[N],tot;
int ans;
int bl[M],br[M];
int tag[M];
int to[N];
struct node{
    int id;//原下标
    int s;//s[i]=suma[i]-sumb[i]
    int w;
    int sw;
}p[N];
void build(int i){
    sort(p+bl[i],p+br[i]+1,[](node nd1,node nd2){
        return nd1.s<nd2.s;
    });
    p[bl[i]].sw=p[bl[i]].w;
    for1(j,bl[i],br[i]){
        to[p[j].id]=j;
        if(j!=bl[i])
            p[j].sw=p[j-1].sw+p[j].w;//mistake2:前缀处理不当 
    }
}
void ins(int x){
    int idd=x/B;
    for1(i,x,br[idd]){
        ans+=1ll*p[to[i]].w*(p[to[i]].s+tag[idd]>=0?1:-1);
        p[to[i]].s++;//mistake3:s打成w 
    }
    build(idd);//mistake4:忘记加build 
    for1(i,idd+1,tot/B){//mistake5:tot打成n 
        int l=bl[i],r=br[i],res=-1;
        while(l<=r){
            int mid=l+r>>1;
            if(p[mid].s+tag[i]>=0) res=mid,r=mid-1;
            else l=mid+1;
        }
        if(res==-1) ans-=p[br[i]].sw;
        else if(res==bl[i]) ans+=p[br[i]].sw;//mistake6:bl打成br 
        else {
            ans-=p[res-1].sw;
            ans+=p[br[i]].sw-p[res-1].sw;
        }
        tag[i]++;
    }
}
void del(int x){
    int idd=x/B;
    for1(i,x,br[idd]){
        ans+=1ll*p[to[i]].w*(p[to[i]].s+tag[idd]<=0?1:-1);
        p[to[i]].s--;//mistake3:s打成w 
    }
    build(idd);
    for1(i,idd+1,tot/B){//mistake5:tot打成n 
        int l=bl[i],r=br[i],res=-1;
        while(l<=r){
            int mid=l+r>>1;
            if(p[mid].s+tag[i]<=0) res=mid,l=mid+1;
            else r=mid-1;
        }
        if(res==-1) ans-=p[br[i]].sw;
        else if(res==br[i]) ans+=p[br[i]].sw;
        else {
            ans+=p[res].sw;
            ans-=p[br[i]].sw-p[res].sw;
        }
        tag[i]--;
    }
}
void solve(){
    cin>>n; 
    for1(i,1,n) cin>>a[i],t[++tot]=a[i];
    for1(i,1,n) cin>>b[i],t[++tot]=b[i];
    cin>>q;
    for1(i,1,q) cin>>idx[i]>>pos[i],t[++tot]=pos[i];
    sort(t+1,t+1+tot);
    tot=unique(t+1,t+1+tot)-t-1;
    auto val=[&](int x)->int{return lower_bound(t+1,t+1+tot,x)-t;};
    for1(i,1,n) p[val(a[i])].s++,p[val(b[i])].s--;
    t[tot+1]=t[tot];
    for1(i,1,tot) p[i].w=t[i+1]-t[i],p[i].s+=p[i-1].s,ans+=abs(p[i].s)*p[i].w,p[i].id=i;//mistake2:前缀处理不当 
    cout<<ans<<"\n";
    B=sqrt(tot),bl[0]++;
    for1(i,0,tot/B)
        bl[i]+=i*B,br[i]=min((i+1)*B-1,tot);//mistake1: 没有-1 
    for1(i,0,tot/B)
        build(i);
    for1(ii,1,q){
        int xx=val(a[idx[ii]]),yy=val(pos[ii]);
        del(xx);
        ins(yy);
        a[idx[ii]]=pos[ii];
        cout<<ans<<"\n";
    }
    return ;
}