BZOJ 1922: [Sdoi2010] continental hegemony Dijkstra

Code: 

#include <queue>  
#include <vector>   
#include <cstdio> 
#include <cstring>  
#include <algorithm>   
#define N 3004 
#define M 70004 
#define ll long long  
#define setIO(s) freopen(s".in","r",stdin) 
using namespace std;    
int edges,n,m; 
vector<int>G[N];    
ll arrive[N],into[N],d[N];     
int hd[N],to[M<<1],nex[M<<1],val[M<<1],deg[N],done[N];         
void addedge(int u,int v,int c) 
{
    nex[++edges]=hd[u],hd[u]=edges,to[edges]=v,val[edges]=c;   
}
struct Node 
{ 
    int u;    
    ll dis; 
    Node(int u=0,ll dis=0):u(u),dis(dis){}    
    bool operator<(Node b) const 
    {
        return b.dis<dis;   
    }
}; 
priority_queue<Node>q;       
void Dijkstra() 
{ 
    int s = 1;    
    memset(d,0x3f,sizeof(d));  
    memset(arrive,0x3f,sizeof(arrive));   
    d[s]=arrive[s]=into[s]=deg[s]=0, q.push(Node(s,0));   
    for(;!q.empty();) 
    {
        Node 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(arrive[v]>d[u]+val[i]) 
            {
                arrive[v]=d[u]+val[i];  
                if(deg[v]==0) 
                {
                    d[v]=max(into[v], arrive[v]);    
                    q.push(Node(v, d[v]));     
                }             
            }
        }   
        for(int i=0;i<G[u].size();++i) 
        {
            int v=G[u][i]; 
            --deg[v];   
            into[v]=max(into[v], d[u]);    
            if(deg[v]==0) 
            {
                d[v]=max(into[v], arrive[v]);    
                q.push(Node(v, d[v]));   
            }
        }
    }
}
int main() 
{  
    int i,j; 
    // setIO("input"); 
    scanf("%d%d",&n,&m);   
    for(i=1;i<=m;++i) 
    {
        int a,b,c; 
        scanf("%d%d%d",&a,&b,&c),addedge(a,b,c);   
    } 
    for(i=1;i<=n;++i) 
    {
        int t,k; 
        scanf("%d",&t); 
        for(j=1;j<=t;++j) 
        {
            ++deg[i],scanf("%d",&k),G[k].push_back(i);      
        }
    } 
    Dijkstra();   
    printf("%lld\n",d[n]);      
    return 0;   
}