poj 2449 Remmarguts' Date 第K短路

题意：给一个有向图，告诉起点和终点，求第K短路

解法：dijkstra+A*，正反两个邻接表

总结：做完这个题学会了dijkstra算法，对A*有了一点了解

PS.优先队列里的比较函数变量写错了，MLE了3天，恶心死我了。膜拜无语神牛，几分钟就指导我搞定了

/*
Problem: 2449		User: fancy081
Memory: 6472K		Time: 250MS
Language: C++		Result: Accepted
*/
#include<cstdio>
#include<queue>
#include<cstring>
using namespace std;

const int MAXN=1005;
const int MAXM=100005;
const int INF=100000000;

int N,M,Start,Te,Kth;
short v[MAXM],rev[MAXM],w[MAXM];
int next[MAXM];
int renext[MAXM];
int first[MAXN],refirst[MAXN];
int h[MAXN];

struct nod
{
	int len,pos;
	bool operator<(const nod &x)const
	{
		return x.len<len;
	}
};
priority_queue<nod> Que;

void dijkstra()
{
	bool done[MAXN];
	while(!Que.empty()) Que.pop();
	for(int i=1;i<=N;i++) {h[i]=INF;done[i]=false;}
	h[Te]=0;	
	nod tmp,iq;
	tmp.len=0;tmp.pos=Te;
	Que.push(tmp);
	int uu,vv,dd;
	while(!Que.empty())
	{
		tmp=Que.top();Que.pop();
		uu=tmp.pos;
		if(done[uu]) continue;
		dd=tmp.len;
		done[uu]=true;
		for(vv=refirst[uu];vv!=-1;vv=renext[vv])
		{
			if(dd+w[vv]<h[rev[vv]])
			{
				h[rev[vv]]=dd+w[vv];
				iq.len=h[rev[vv]];
				iq.pos=rev[vv];
				Que.push(iq);			
			}
		}
	}
}

struct nodx
{
	int f,pos;
	bool operator<(const nodx &x)const
	{
		return x.f<f;
	}
};
priority_queue<nodx> Quex;
int astar()
{
	nodx tmp,iq;
	while(!Quex.empty()) Quex.pop();
	int cnt[MAXN];
	for(int i=1;i<=N;i++) cnt[i]=0;
	tmp.f=h[Start];tmp.pos=Start;
	Quex.push(tmp);
	int ff,now,gg,vv;
	while(!Quex.empty())
	{
		tmp=Quex.top();Quex.pop();
		ff=tmp.f;now=tmp.pos;
		gg=tmp.f-h[now];
		cnt[now]++;
		if(cnt[now]>Kth) continue;
		if(cnt[Te]==Kth) return ff;
		for(vv=first[now];vv!=-1;vv=next[vv])
		{
			iq.f=gg+w[vv]+h[v[vv]];
			iq.pos=v[vv];
			Quex.push(iq);
		}
	}
	return -1;
}

int main()
{
	while(scanf("%d%d",&N,&M)!=EOF)
	{
		for(int i=0;i<=N;i++) {first[i]=-1;refirst[i]=-1;}
		for(int e=0;e<M;e++)
		{
			scanf("%d%d%d",&rev[e],&v[e],&w[e]);
			next[e]=first[rev[e]];
			first[rev[e]]=e;
			renext[e]=refirst[v[e]];
			refirst[v[e]]=e;
		}		
		scanf("%d%d%d",&Start,&Te,&Kth);
		if(Start==Te) Kth++;
		dijkstra();
	        printf("%d\n",astar());
	}
	return 0;
}