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;
}