关于最短路算法

int dis[N];
struct node{
    int x,d;
    node(){}
    node(int a,int b){x=a;d=b;}
    bool operator < (node a)const{
        return d>a.d;
    }
};
priority_queue<node> q;
void dij(){
    memset(dis,0x3f,sizeof(dis));
    dis[1]=0;q.push(node(1,0));
    while(!q.empty()){
        int x=q.top().x;q.pop();
        for(int i=head[x];i;i=nxt[i]){
            int y=to[i];
            // cout<<endl<<"SB"<<" "<<x<<" "<<dis[x]<<" "<<len[i]<<" "<<y<<" "<<dis[y]<<endl;
            if(dis[y]<=dis[x]+len[i])continue;
            dis[y]=dis[x]+len[i];
            q.push(node(y,dis[y]));
        }
    }
}