P4568 飞行路线

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#include<bits/stdc++.h>
using namespace std;const int N=10010,M=100010,K=15;
int h[N],ne[M],e[M],idx,w[M];
int dist[N][K];
int st[N][K];
int n,m,k;
int s,t;void add(int a,int b,int c)
{e[idx]=b,ne[idx]=h[a],w[idx]=c,h[a]=idx++;
}struct Node{int cost;int id;int k;bool operator>(const Node& other) const{return cost>other.cost;}
}node;void dijkstra()
{memset(dist,0x3f,sizeof dist);priority_queue<Node,vector<Node>,greater<Node>> heap;dist[s][0]=0;heap.push({dist[s][0],s,0});while(!heap.empty()){auto t=heap.top();heap.pop();int u=t.id;int d=t.cost;int cnt=t.k;if(st[u][cnt]) continue;st[u][cnt]=true;for(int i=h[u];i!=-1;i=ne[i]){int j=e[i];if(dist[j][cnt]>d+w[i]){dist[j][cnt]=d+w[i];heap.push({dist[j][cnt],j,cnt});}if(cnt<k&&dist[j][cnt+1]>d){dist[j][cnt+1]=d;heap.push({dist[j][cnt+1],j,cnt+1});}}}
}int main()
{ios::sync_with_stdio(0),cin.tie(0);memset(h,-1,sizeof h);cin>>n>>m>>k;cin>>s>>t;for(int i=0;i<m;i++){int a,b,c;cin>>a>>b>>c;add(a,b,c);add(b,a,c);}dijkstra();int ans=0x3f3f3f3f;for(int i=0;i<=k;i++){ans=min(dist[t][i],ans);}cout<<ans<<endl;return 0;
}