BZOJ 3073: [Pa2011]Journeys Dijkstra+线段树优化建图

复习一下线段树优化建图：
1.两颗线段树的叶子节点的编号是公用的.
2.每次连边是要建两个虚拟节点 $p1,p2$ 并在 $p1,p2$ 之间连边.

#include <bits/stdc++.h>
#define N 8000034
#define ls t[x].lson
#define rs t[x].rson
#define inf 1000000000
#define setIO(s) freopen(s".in","r",stdin) ,freopen(s".out","w",stdout)
using namespace std;
int edges,tot,n,m,s,rtin,rtout;
int hd[N],to[N],nex[N],val[N],d[N],done[N];
void addedge(int u,int v,int c)
{
    nex[++edges]=hd[u],hd[u]=edges,to[edges]=v,val[edges]=c;
}
int newnode()
{
    return ++tot;
}
struct Node
{
    int lson,rson;
}t[N];
struct P
{
    int u,dis;
    P(int u=0,int dis=0):u(u),dis(dis){}
    bool operator<(P b) const
    {
        return b.dis<dis;
    }
};
priority_queue<P>q;
namespace segin
{
    void build(int l,int r,int &x)
    {
        if(l==r)
        {
            x=l;
            return;
        }
        else
        {
            x=newnode();
        }
        int mid=(l+r)>>1;
        if(l<=mid) build(l,mid,ls),addedge(x,ls,0);
        if(r>mid)  build(mid+1,r,rs),addedge(x,rs,0);
    }
    void Add(int l,int r,int x,int L,int R,int p)
    {
        if(l>=L&&r<=R)
        {
            addedge(p,x,0);
            return;
        }
        int mid=(l+r)>>1;
        if(L<=mid) Add(l,mid,ls,L,R,p);
        if(R>mid)  Add(mid+1,r,rs,L,R,p);
    }
};
namespace segout
{
    void build(int l,int r,int &x)
    {
        if(l==r)
        {
            x=l;
            return;
        }
        else
        {
            x=newnode();
        }
        int mid=(l+r)>>1;
        if(l<=mid) build(l,mid,ls),addedge(ls,x,0);
        if(r>mid)  build(mid+1,r,rs),addedge(rs,x,0);
    }
    void Add(int l,int r,int x,int L,int R,int p)
    {
        if(l>=L&&r<=R)
        {
            addedge(x,p,0);
            return;
        }
        int mid=(l+r)>>1;
        if(L<=mid) Add(l,mid,ls,L,R,p);
        if(R>mid)  Add(mid+1,r,rs,L,R,p);
    }
};
void Add(int l1,int r1,int l2,int r2,int w)
{
    int p1=newnode(),p2=newnode();
    addedge(p1,p2,w);
    segout::Add(1,n,rtout,l1,r1,p1);
    segin::Add(1,n,rtin,l2,r2,p2);
}
void Dijkstra()
{
    for(int i=0;i<N;++i) d[i]=inf;
    for(d[s]=0,q.push(P(s,0));!q.empty();)
    {
        P e=q.top();
        q.pop();
        int u=e.u;
        if(done[u]) continue;
        done[u]=1;
        for(int i=hd[u];i;i=nex[i])
        {
            int v=to[i];
            if(d[v]>d[u]+val[i])
            {
                d[v]=d[u]+val[i];
                q.push(P(v,d[v]));
            }
        }
    }
}
int main()
{
    int i,j;
    // setIO("input");
    scanf("%d%d%d",&n,&m,&s);
    tot=n;
    segin::build(1,n,rtin);
    segout::build(1,n,rtout);
    for(i=1;i<=m;++i)
    {
        int l1,r1,l2,r2;
        scanf("%d%d%d%d",&l1,&r1,&l2,&r2);
        Add(l1,r1,l2,r2,1);
        Add(l2,r2,l1,r1,1);
    }
    Dijkstra();
    for(i=1;i<=n;++i) printf("%d\n",d[i]);
    return 0;
}