bzoj3681: Arietta（网络流）

传送门

主席树优化建图？

然而我连代码都看不懂

贴个题解好了->这里

 //minamoto
 #include<iostream>
 #include<cstdio>
 #include<cstring>
 #include<queue>
 #include<vector>
 #define inf 0x3f3f3f3f
 using namespace std;
 #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;
 }
 const int N=;
 int head[N*],dep[N*],cur[N*],ver[N*],edge[N*],Next[N*],tot=;
 int fa[N],L[N*],R[N*],sz[N],son[N],rt[N],v[N];
 queue<int> q;vector<int> ch[N];int S,T,cnt,n,m;
 inline void add(int u,int v,int e){
     ver[++tot]=v,Next[tot]=head[u],head[u]=tot,edge[tot]=e;
     ver[++tot]=u,Next[tot]=head[v],head[v]=tot,edge[tot]=;
 }
 bool bfs(){
     while(!q.empty()) q.pop();
     for(int i=S;i<=T;++i) cur[i]=head[i];
     memset(dep,-,sizeof(dep));
     q.push(S),dep[S]=;
     while(!q.empty()){
         int u=q.front();q.pop();
         for(int i=head[u];i;i=Next[i]){
             int v=ver[i];
             if(dep[v]<&&edge[i]){
                 dep[v]=dep[u]+,q.push(v);
                 if(v==T) return true;
             }
         }
     }
     return false;
 }
 int dfs(int u,int limit){
     if(u==T||!limit) return limit;
     int flow=,f;
     for(int i=cur[u];i;cur[u]=i=Next[i]){
         int v=ver[i];
         if(dep[v]==dep[u]+&&(f=dfs(v,min(limit,edge[i])))){
             flow+=f,limit-=f;
             edge[i]-=f,edge[i^]+=f;
             if(!limit) break;
         }
     }
     if(!flow) dep[u]=-;
     return flow;
 }
 int dinic(){
     int flow=;
     while(bfs()) flow+=dfs(S,inf);
     return flow;
 }
 void update(int &p,int x,int l,int r,int a,int b){
     p=++cnt;
     if(l==r){
         add(p+n,b,inf);
         if(x) add(p+n,x+n,inf);
         return;
     }
     int mid=l+r>>;
     if(a<=mid) R[p]=R[x],update(L[p],L[x],l,mid,a,b);
     else L[p]=L[x],update(R[p],R[x],mid+,r,a,b);
 }
 inline void getall(int x,int y){
     update(rt[x],rt[x],,n,v[y],y);
     for(int i=,s=ch[y].size();i<s;++i) getall(x,ch[y][i]);
 }
 void DFS(int u){
     sz[u]=;
     for(int i=,s=ch[u].size();i<s;++i){
         int v=ch[u][i];
         DFS(v),sz[u]+=sz[v];
         if(sz[v]>sz[son[u]]) son[u]=v;
     }
     update(rt[u],rt[son[u]],,n,v[u],u);
     for(int i=,s=ch[u].size();i<s;++i)
     if(ch[u][i]!=son[u]) getall(u,ch[u][i]);
 }
 void query(int p,int l,int r,int ql,int qr,int x){
     if(!p) return;
     if(ql<=l&&qr>=r) return (void)(add(x+n,p+n,inf));
     int mid=l+r>>;
     if(ql<=mid) query(L[p],l,mid,ql,qr,x);
     if(qr>mid) query(R[p],mid+,r,ql,qr,x);
 }
 int main(){
     //freopen("testdata.in","r",stdin);
     n=read(),m=read();
     for(int i=;i<=n;++i) fa[i]=read(),ch[fa[i]].push_back(i);
     for(int i=;i<=n;++i) v[i]=read();
     DFS();
     S=;
     for(int i=;i<=cnt;++i){
         if(L[i]) add(i+n,L[i]+n,inf);
         if(R[i]) add(i+n,R[i]+n,inf);
     }
     for(int i=;i<=m;++i){
         int l=read(),r=read(),p=read(),t=read();
         add(S,(++cnt)+n,t);
         query(rt[p],,n,l,r,cnt);
     }
     T=cnt+n+;
     for(int i=;i<=n;++i) add(i,T,);
     printf("%d\n",dinic());
     return ;
 }