作者:
沫羽皓
,
2023-05-27 06:45:52
,
所有人可见
,
阅读 8
#include<cstring>
#include<algorithm>
#include<iostream>
using namespace std;
const int N=510,M=100010;
struct Edge
{
int a,b,c;
}edges[M];
int n,m,k;
int dist[N];
int last[N];
void bellman_ford()
{
memset(dist,0x3f,sizeof dist);
dist[1]=0;
for(int i=0;i<k;++i)
{
memcpy(last,dist,sizeof dist);
for(int j=0;j<m;++j)
{
auto e=edges[j];
dist[e.b]=min(dist[e.b],last[e.a]+e.c);
}
}
}
int main()
{
cin>>n>>m>>k;
for(int i=0;i<m;++i)
{
int a,b,c;
scanf("%d%d%d",&a,&b,&c);
edges[i]={a,b,c};
}
bellman_ford();
if(dist[n]>0x3f3f3f3f/2)puts("impossible");
else cout<<dist[n]<<endl;
return 0;
}