模板题
#include<iostream>
#include<queue>
#include<string.h>
#include<stdio.h>
using namespace std;
#define inf 0x3f3f3f3f
struct node
{
int id,f,g;
};
struct edge
{
int u,v,val,next;
}e[100005],eopp[100005];
struct cmp
{
bool operator()(const struct node &a,const struct node &b)
{
return a.f>b.f; //表示按结构体变量里的x成员为比较要素，升序排列
}
};
int head[1005],headopp[1005],disopp[1005],visopp[1005],cnt[1005]={0};
int n,m,s,t,k;
priority_queue<struct node,vector<struct node>,cmp>mq;
void spfa(int v0)
{
disopp[v0]=0;
queue<int>q;
while(!q.empty()) q.pop();
q.push(v0);
visopp[v0]=1;
while(!q.empty())
{
int u=q.front();
q.pop();
visopp[u]=0;
for(int i=headopp[u];i!=-1;i=eopp[i].next)
{
int v=eopp[i].v;
int w=eopp[i].val;
if(disopp[v]>disopp[u]+w)
{
disopp[v]=disopp[u]+w;
if(!visopp[v])
{
q.push(v);
visopp[v]=1;
}
}
}
}
}
int astar()
{
struct node tmp;
tmp.id=s;
tmp.g=0;
tmp.f=disopp[s];
mq.push(tmp);
while(!mq.empty())
{
node now=mq.top();
mq.pop();
cnt[now.id]++;
if(cnt[now.id]>k) continue;
if(cnt[t]==k) return now.g;
for(int i=head[now.id];i!=-1;i=e[i].next)
{
node next;
next.id=e[i].v;
next.g=now.g+e[i].val;
next.f=next.g+disopp[next.id];;
mq.push(next);
}
}
return -1;
}
int main()
{
int b=0;
cin>>n>>m;
memset(head,-1,sizeof(head));
memset(headopp,-1,sizeof(headopp));
memset(disopp,0x3f,sizeof(disopp));
memset(visopp,0,sizeof(visopp));
for(int i=1;i<=m;i++)
{
int u,v,w;
scanf("%d%d%d",&u,&v,&w);
e[b].u=u;
e[b].v=v;
e[b].val=w;
e[b].next=head[u];
head[u]=b;
eopp[b].u=v;
eopp[b].v=u;
eopp[b].val=w;
eopp[b].next=headopp[v];
headopp[v]=b;
b++;
}
scanf("%d%d%d",&s,&t,&k);
//cout<<"****"<<endl;
//cout<<"正边"<<endl;
//for(int i=1;i<=n;i++)
//{
//for(int j=head[i];j!=-1;j=e[j].next)
//cout<<e[j].u<<" "<<e[j].v<<" "<<e[j].val<<endl;
//}
//cout<<"反边"<<endl;
//for(int i=1;i<=n;i++)
//{
//for(int j=headopp[i];j!=-1;j=eopp[j].next)
//cout<<eopp[j].u<<" "<<eopp[j].v<<" "<<eopp[j].val<<endl;
//}
if(s==t) k++;
spfa(t);
printf("%d\n",astar());
return 0;
}