bzoj4889: [Tjoi2017]不勤劳的图书管理员（树套树）

传送门

据说正解线段树套平衡树

然而网上参考（抄）了一个树状数组套动态开点线段树的

思路比较清楚，看代码应该就明白了

 //minamoto
 #include<iostream>
 #include<cstdio>
 #include<cstring>
 #define ll long long
 using namespace std;
 const int N=,mod=1e9+;
 #define getc() (p1==p2&&(p2=(p1=buf)+fread(buf,1,1<<21,stdin),p1==p2)?EOF:*p1++)
 char buf[<<],*p1=buf,*p2=buf;
 inline int read(){
     #define num ch-'0'
     char ch;bool flag=;int res;
     while(!isdigit(ch=getc()))
     (ch=='-')&&(flag=true);
     for(res=num;isdigit(ch=getc());res=res*+num);
     (flag)&&(res=-res);
     #undef num
     return res;
 }
 char sr[<<],z[];int C=-,Z;
 inline void Ot(){fwrite(sr,,C+,stdout),C=-;}
 inline void print(ll x){
     if(C><<)Ot();if(x<)sr[++C]=,x=-x;
     while(z[++Z]=x%+,x/=);
     while(sr[++C]=z[Z],--Z);sr[++C]='\n';
 }
 int n,m,a[N],b[N],c[N],cntt[N];
 ll ans;
 inline void add(int x,int y){
     for(;x<=n;x+=x&-x) c[x]+=y,++cntt[x];
 }
 inline ll sum_v(int x){
     ll res=;
     for(;x;x-=x&-x) res+=c[x];return res;
 }
 inline ll sum_cnt(int x){
     ll res=;
     for(;x;x-=x&-x) res+=cntt[x];return res;
 }
 int tot,rt[N],cnt[N<<],L[N<<],R[N<<];ll v[N<<];
 void insert(int &p,int l,int r,int x,int k,int t){
     if(!p) p=++tot;v[p]+=k,cnt[p]+=t;
     if(l==r) return;int mid=l+r>>;
     if(x<=mid) insert(L[p],l,mid,x,k,t);
     else insert(R[p],mid+,r,x,k,t);
 }
 inline void add(int x,int y,int k,int t){
     for(;x<=n;x+=x&-x) insert(rt[x],,n,y,k,t);
 }
 int query_v(int p,int l,int r,int ql,int qr){
     if(!p) return ;
     if(ql<=l&&qr>=r) return v[p];int mid=l+r>>;
     int res=;
     if(ql<=mid) res+=query_v(L[p],l,mid,ql,qr);
     if(qr>mid) res+=query_v(R[p],mid+,r,ql,qr);
     return res;
 }
 int query_cnt(int p,int l,int r,int ql,int qr){
     if(!p) return ;
     if(ql<=l&&qr>=r) return cnt[p];int mid=l+r>>;
     int res=;
     if(ql<=mid) res+=query_cnt(L[p],l,mid,ql,qr);
     if(qr>mid) res+=query_cnt(R[p],mid+,r,ql,qr);
     return res;
 }
 ll Q_v(int l,int r,int ql,int qr){
     if(l>r||ql>qr) return ;
     ll res=;
     for(;r;r-=r&-r) res+=query_v(rt[r],,n,ql,qr);
     for(--l;l;l-=l&-l) res-=query_v(rt[l],,n,ql,qr);return res;
 }
 ll Q_cnt(int l,int r,int ql,int qr){
     if(l>r||ql>qr) return ;
     ll res=;
     for(;r;r-=r&-r) res+=query_cnt(rt[r],,n,ql,qr);
     for(--l;l;l-=l&-l) res-=query_cnt(rt[l],,n,ql,qr);return res;
 }
 inline void dec(ll &x,ll y){
     while(x<y) x+=mod;x-=y;
 }
 int main(){
     //freopen("testdata.in","r",stdin);
     n=read(),m=read();
     for(int i=;i<=n;++i) a[i]=read(),b[i]=read();
     for(int i=n;i;--i) add(a[i],b[i]),(ans+=sum_v(a[i]-)+sum_cnt(a[i]-)*b[i])%=mod;
     for(int i=;i<=n;++i) add(i,a[i],b[i],);
     while(m--){
         int l=read(),r=read();
         if(l>r) swap(l,r);
         if(l==r) {print(ans);continue;}
         (ans+=Q_v(l+,r-,,a[r]-))%=mod;
         (ans+=Q_cnt(l+,r-,,a[r]-)*b[r])%=mod;
         dec(ans,Q_v(l+,r-,a[r]+,n));
         dec(ans,Q_cnt(l+,r-,a[r]+,n)*b[r]);
         (ans+=Q_v(l+,r-,a[l]+,n))%=mod;
         (ans+=Q_cnt(l+,r-,a[l]+,n)*b[l])%=mod;
         dec(ans,Q_v(l+,r-,,a[l]-));
         dec(ans,Q_cnt(l+,r-,,a[l]-)*b[l]);
         if(a[l]>a[r]) dec(ans,b[l]+b[r]);
         else (ans+=b[l]+b[r])%=mod;
         add(l,a[l],-b[l],-),add(l,a[r],b[r],);
         add(r,a[r],-b[r],-),add(r,a[l],b[l],);
         swap(a[l],a[r]),swap(b[l],b[r]);
         print(ans);
     }
     Ot();
     return ;
 }