HDU 5669 线段树优化建图+分层图最短路

用线段树维护建图，即把用线段树把每个区间都标号了，Tree1中子节点有到达父节点的单向边，Tree2中父节点有到达子节点的单向边.

每次将源插入Tree1,汇插入Tree2,中间用临时节点相连。那么Tree1中的所用子节点都可以到达，Tree2中的所用子节点。　

感觉很有道理啊，以前从来没用用线段树这样维护过建图。分层图最短路没有像BZOJ2763可以直接向先一层连边，因为边已经很多了。

 #include <cstdio>
 #include <iostream>
 #include <cstring>
 #include <algorithm>
 #include <queue>
 #include <vector>
 #define pa pair<int,int>
 #define pa3 pair<int,pa>
 #define mp make_pair
 #define fi first
 #define se second
 #define pb push_back
 using namespace std;
 const int Maxn=;
 const int Maxk=;
 struct Edge{int to,next,w;}edge[Maxn<<];
 vector<int> P1,P2;
 priority_queue<pa3,vector<pa3>,greater<pa3> > Q;
 int n,m,Id1[Maxn],Id2[Maxn],head[Maxn],dis[Maxn][Maxk],cnt,Block;
 int Kase,v,k;
 inline void Add(int u,int v,int w)
 {edge[cnt].to=v;edge[cnt].next=head[u];edge[cnt].w=w;head[u]=cnt++;}
 inline int Max(int x,int y) {return x>y?x:y;}
 inline void Get_Int(int &x)
 {
     x=;  char ch=getchar(); int f=;
     while (ch<'' || ch>'') {if (ch=='-') f=-; ch=getchar();}
     while (ch>='' && ch<='') {x=x*+ch-''; ch=getchar();} x*=f;
 }
 inline void Put_Int(int x)
 {
     char ch[]; int top=;
     if (x==) ch[++top]='';
     while (x) ch[++top]=x%+'',x/=;
     while (top) putchar(ch[top--]); putchar('\n');
 }
 void Build1(int o,int l,int r)
 {
     Block=Max(Block,o);
     if (l==r) {Id1[l]=o; return;}
     int mid=(l+r)>>;
     Build1(o<<,l,mid),Build1(o<<|,mid+,r);
     Add(o<<,o,),Add(o<<|,o,);
 }
 void Build2(int o,int l,int r)
 {
     if (l==r) {Id2[l]=Block+o; Add(Id2[l],Id1[l],);return;}
     int mid=(l+r)>>;
     Build2(o<<,l,mid),Build2(o<<|,mid+,r);
     Add(Block+o,Block+(o<<),),Add(Block+o,Block+(o<<|),);
 }
 void Modify1(int o,int l,int r,int p,int q)
 {
     if (l==p && r==q) {P1.pb(o); return;}
     int mid=(l+r)>>;
     if (q<=mid) Modify1(o<<,l,mid,p,q);
     if (p>=mid+) Modify1(o<<|,mid+,r,p,q);
     if (p<=mid && q>=mid+)
     Modify1(o<<,l,mid,p,mid),Modify1(o<<|,mid+,r,mid+,q);
 }
 void Modify2(int o,int l,int r,int p,int q)
 {
     if (l==p && r==q) {P2.pb(o+Block); return;}
     int mid=(l+r)>>;
     if (q<=mid) Modify2(o<<,l,mid,p,q);
     if (p>=mid+) Modify2(o<<|,mid+,r,p,q);
     if (p<=mid && q>=mid+)
     Modify2(o<<,l,mid,p,mid),Modify2(o<<|,mid+,r,mid+,q);
 }
 
 void Dij()
 {
     memset(dis,0x7f,sizeof(dis));
     Q.push(mp(,mp(Id1[],))); dis[Id1[]][]=;
     while (!Q.empty())
     {
         int u=Q.top().se.fi,v=Q.top().se.se; Q.pop();
         for (int i=head[u];i!=-;i=edge[i].next)
         {
             if (dis[edge[i].to][v]>dis[u][v]+edge[i].w)
             {
                 dis[edge[i].to][v]=dis[u][v]+edge[i].w;
                 Q.push(mp(dis[edge[i].to][v],mp(edge[i].to,v)));
             }
             if (v<k)
             {
                 if (dis[edge[i].to][v+]>dis[u][v])
                 {
                     dis[edge[i].to][v+]=dis[u][v];
                     Q.push(mp(dis[edge[i].to][v+],mp(edge[i].to,v+)));
                 }
             }
         }
     }
 }        
 
 int main()
 {
     Get_Int(Kase);
     for (int kase=;kase<=Kase;kase++)
     {
         Get_Int(n),Get_Int(m),Get_Int(k);
         memset(head,-,sizeof(head)); Block=;
         Build1(,,n); Block++; Build2(,,n);
         int tot=(Block<<)+,a,b,c,d,w;
         for (int i=;i<=m;i++)
         {
             Get_Int(a),Get_Int(b),Get_Int(c),Get_Int(d),Get_Int(w);
             P1.clear(),P2.clear();
             Modify1(,,n,a,b);
             Modify2(,,n,c,d);
             tot++;
             for (int j=;j<P1.size();j++) Add(P1[j],tot,w);
             for (int j=;j<P2.size();j++) Add(tot,P2[j],);
 
             P1.clear(),P2.clear();
             Modify1(,,n,c,d);
             Modify2(,,n,a,b);
             tot++;
             for (int j=;j<P1.size();j++) Add(P1[j],tot,w);
             for (int j=;j<P2.size();j++) Add(tot,P2[j],);
         }
     }
     Dij();
     if (dis[Id2[n]][k]==0x7fffffff) puts("CreationAugust is a sb!"); else
         Put_Int(dis[Id2[n]][k]);
     return ;
 }

把标答代码改成Dij系列..