LibreOJ #119. 最短路

Posted 2020-09-24 ZlycerQan

二次联通门 : LibreOJ #119. 最短路

 

 

 

 

/*
    LibreOJ #119. 最短路 
    
    堆优化的Dijkstra
     
*/
#include <cstring>
#include <cstdio>
#include <queue>

#define Max 6000

void read (int &now)
{
    now = 0;
    register char word = getchar ();
    while (word < ‘0‘ || word > ‘9‘)
        word = getchar ();
    while (word >= ‘0‘ && word <= ‘9‘)
    {
        now = now * 10 + word - ‘0‘;
        word = getchar ();
    }
}

struct Data
{
    int Id;
    int dis;

    bool operator < (const Data &now) const
    {
        return this->dis > now.dis;
    }
    
    Data (int __Id, int __dis) : Id (__Id), dis (__dis) {};
    
    Data () {};
};


class Dijkstra_Type
{
    
    private :
        
        int __to[Max << 3], __next[Max << 3];
        int __dis[Max << 3];
        
        int Edge_Count;
        int edge_list[Max];
        bool visit[Max];
        
        int dis[Max];
        
    public :
        
        void Insert_edge (int from, int to, int dis)
        {
            Edge_Count ++;
            
            __to[Edge_Count] = to;
            __next[Edge_Count] = edge_list[from];
            edge_list[from] = Edge_Count;
            
            Edge_Count ++;
            
            __to[Edge_Count] = from;
            __next[Edge_Count] = edge_list[to];
            edge_list[to] = Edge_Count;
            
            __dis[Edge_Count] = __dis[Edge_Count - 1] = dis;
        }
        
        int Dijkstra (int Start, int End)
        {
            std :: priority_queue <Data> Queue;
            
            memset (dis, 0x3f, sizeof dis);
            
            Data now ;
            
            for (Queue.push (Data (Start, 0)), dis[Start] = 0; !Queue.empty (); Queue.pop ())
            {
                now = Queue.top ();
                
                if (visit[now.Id])
                    continue;
                    
                visit[now.Id] = true;
                
                for (int i = edge_list[now.Id]; i; i = __next[i])
                
                    if (dis[__to[i]] > dis[now.Id] + __dis[i])
                    {
                        dis[__to[i]] = dis[now.Id] + __dis[i];
                        Queue.push (Data (__to[i], dis[__to[i]]));
                    }
            }
            return dis[End];
        }
};

Dijkstra_Type Make;

int main (int argc, char *argv[])
{
    int N, M;
    int x, y, z;
    
    int S, T;
    for (read (N), read (M), read (S), read (T); M --; )
    {
        read (x);
        read (y);
        read (z);
        
        Make.Insert_edge (x, y, z);
    }
    
    printf ("%d", Make.Dijkstra (S, T));
    
    return 0;
}