【2014-3】day3 T2 攻城略池

来源：互联网发布：路由器封端口编辑：程序博客网时间：2024/04/27 14:29

参观wwx的代码，这暴力简直神了，我太弱，有些细节还是没看懂

#include <iostream>#include <cstdio>#include <cstdlib>#include <algorithm>#include <cstring>#include <cmath>#include <string>using namespace std;const int Maxn=100005,inf=999999999+208;typedef long long LL;int n,d[Maxn],ans=0;int fst[Maxn],next[Maxn*2],to[Maxn*2],dis[Maxn*2],En=0;int dist[Maxn],fa[Maxn],Q[Maxn];int get(){   int v;char ch;   while (!isdigit(ch=getchar()));v=ch-48;   while (isdigit(ch=getchar()))v=v*10+ch-48;return v;}struct node *null;struct node{   int k;LL b;//y=kx-b   node *lc,*rc;   inline node(){k=0;b=0;lc=rc=null;}}Tnull;class Segment_Tree{   node *root;   void Insert(node *&x,int l,int r,int k,int b)   {      if (x==null) x=new node();      x->k+=k;x->b+=b;      if (l==r) return;int mid=(l+r)>>1;      if (b<=mid) Insert(x->lc,l,mid,k,b);      else Insert(x->rc,mid+1,r,k,b);   }   int qry(node *x,int l,int r,int D,int k,LL b)   {      if (l==r) return l;      int mid=(l+r)>>1;      if ((LL)(x->lc->k+k)*mid-b-x->lc->b>=D) return qry(x->lc,l,mid,D,k,b);      return qry(x->rc,mid+1,r,D,k+x->lc->k,b+x->lc->b);   }   node *Merge(node *x,node *y)   {      if (x==null) return y;      if (y==null) return x;      x->k+=y->k;x->b+=y->b;      x->lc=Merge(x->lc,y->lc);      x->rc=Merge(x->rc,y->rc);delete y;return x;   }   public:      Segment_Tree(){root=null;}      void Insert(int _k,int _b){Insert(root,0,inf,_k,_b);}      int qry(int D,int dis){return qry(root,0,inf,D,0,0)-dis;}      void Merge(Segment_Tree *y){root=Merge(root,y->root);}}*T[Maxn];void addedge(int u,int v,int l){   next[++En]=fst[u];fst[u]=En;to[En]=v;dis[En]=l;   next[++En]=fst[v];fst[v]=En;to[En]=u;dis[En]=l;}void work(){   int l=1,r=2;Q[1]=1;fa[1]=0;   while (l<r)   {      int x=Q[l++];      for (int k=fst[x];k;k=next[k])         if (fa[x]!=to[k]) Q[r++]=to[k],dist[to[k]]=dist[x]+dis[k],fa[to[k]]=x;   }   for (int i=0;i<=n;i++) T[i]=new Segment_Tree();   for (int i=r-1;i;i--)   {      int x=Q[i],Time=0;      if (d[x]) Time=T[x]->qry(d[x],dist[x]);      T[x]->Insert(1,Time+dist[x]);      ans=max(ans,Time);T[fa[x]]->Merge(T[x]);   }}int main(){   freopen("conquer.in","r",stdin);   freopen("conquer.out","w",stdout);   n=get();null=&Tnull;null->lc=null->rc=null;   for (int i=1;i<=n;i++) d[i]=get();   for (int i=1;i<n;i++)   {      int u=get(),v=get(),l=get();addedge(u,v,l);   }   work();   printf("%d\n",ans);   //system("pause");   return 0;}

标程神一样的6kb，有解释就不放了吧~~~

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