K最短路 A*算法

POJ2449 Remmarguts' Date

#include <iostream>
#include <algorithm>
#include <queue>
#include <stdio.h>
using namespace std;
int m,n,s,t,k;
#define M 100005
#define N 1005
#define INF 100000000
int dis[N];
struct edge
{
    int v,val,next;//边的终点，边权
    edge(){}
    edge(int _v,int _val,int _next){v=_v,val=_val,next=_next;}
}line[M],_line[M];
int head[M],_head[M];

struct dijnode
{
    int v,dis;
    dijnode(){}
    dijnode(int _v,int _dis){v=_v,dis=_dis;}
    friend bool operator <(const dijnode &a,const dijnode &b)
    {
        return a.dis>b.dis;
    }
};
struct Anode
{
    int v,g,h;//v:当前点 g:起点到点v距离 h:点v到终点距离
    Anode(){}
    Anode(int _v,int _g,int _h){v=_v,g=_g;h=_h;}
    friend bool operator <(const Anode&a,const Anode&b)
    {
        return a.h+a.g>b.h+b.g;
    }
};
void input(){
    memset(head,-1,sizeof(head));
    memset(_head,-1,sizeof(_head));
    int u,v,val;
    int e=0,_e=0;
    for(int i=0;i<m;i++)
    {
        scanf("%d%d%d",&u,&v,&val);
        line[e]=edge(v,val,head[u]);
        head[u]=e++;
        _line[_e]=edge(u,val,head[v]);
        _head[v]=_e++;
    }
}
int vis[N];
void dijkstra()
{
    memset(vis,0,sizeof(vis));
    priority_queue<dijnode>pq;
    for(int i=0;i<n;i++)
        dis[i]=INF;
    
    dijnode node =dijnode(t,0);
    dis[t]=0;
    pq.push(node);
    
    while(!pq.empty())
    {
        dijnode tmp = pq.top();
        pq.pop();
        
        if(vis[tmp.v])continue;
        vis[tmp.v]=1;
        for(int i=_head[tmp.v];i!=-1;i=_line[i].next)
        {
            if(tmp.dis+_line[i].val<dis[_line[i].v])
            {
                dis[_line[i].v]=tmp.dis+_line[i].val;
                pq.push(dijnode(_line[i].v,dis[_line[i].v]));
            }
        }
    }
    for(int i=1;i<=n;i++)printf("%d
",dis[i]);
    
}
int kcnt[N];
int Astar()
{
    if(dis[s]>=INF)return -1;
    memset(kcnt,0,sizeof(kcnt));
    priority_queue<Anode> pq;
    pq.push(Anode(s,0,dis[s]));
    Anode node;
    while(!pq.empty())
    {
        node = pq.top();
        pq.pop();
        if(kcnt[node.v]>=k)continue;
        
        kcnt[node.v]++;
        if(kcnt[t]>=k)return node.g;
        for(int i=head[node.v];i!=-1;i = line[i].next)
        {
            pq.push(Anode(line[i].v,node.g+line[i].val,dis[line[i].v]));
        }
    }
    return -1;
    
}
int main(int argc, const char * argv[])
{
    
    while(scanf("%d%d",&n,&m)!=EOF)
    {
        input();
        scanf("%d%d%d",&s,&t,&k);
        dijkstra();
        printf("%d
",Astar());
    }
}