题意：中文
思路：我们把每一个牧场作为起点，算出到每一个奶牛在的牧场的最短距离。取个min.
1 #include<bits/stdc++.h> 2 using namespace std; 3 const int Max=803; 4 const int INF=1e8; 5 6 int n,p,c;//牛，牧场，道路// 7 int a[Max],last[Max]; 8 struct node{ 9 int to,next,val; 10 }e[Max*400]; 11 int len,vis[Max],dis[Max]; 12 13 void add(int u,int v,int x){ 14 e[len].to=v;e[len].next=last[u]; 15 e[len].val=x;last[u]=len++; 16 } 17 struct point 18 { 19 int val,id; 20 point(int id,int val):id(id),val(val){} 21 bool operator <(const point &x)const{ 22 return val>x.val; 23 } 24 }; 25 int ss; 26 void hh(int s) 27 { 28 memset(vis,0,sizeof(vis)); 29 for(int i=1;i<=p;i++) 30 dis[i]=INF; 31 priority_queue<point> q; 32 q.push(point(s,0)); 33 dis[s]=0; 34 while(!q.empty()) 35 { 36 int cur=q.top().id; 37 int curr=q.top().val; 38 q.pop(); 39 if(vis[cur]) continue; 40 vis[cur]=true; 41 for(int i=last[cur];i!=-1;i=e[i].next) 42 { 43 int id=e[i].to; 44 if(!vis[id] && curr+e[i].val < dis[id]) 45 { 46 dis[id]=curr+e[i].val; 47 q.push(point(id,dis[id])); 48 } 49 } 50 51 } 52 ss=0; 53 for(int i=1;i<=n;i++) 54 ss+=dis[a[i]]; 55 // cout<<ss<<endl; 56 } 57 int main() 58 { 59 int x,y,z; 60 scanf("%d%d%d",&n,&p,&c); 61 for(int i=1;i<=n;i++) 62 scanf("%d",&a[i]); 63 memset(last,-1,sizeof(last)); 64 for(int i=1;i<=c;i++){ 65 scanf("%d%d%d",&x,&y,&z); 66 add(x,y,z); 67 add(y,x,z); 68 } 69 int Min=INF; 70 for(int i=1;i<=p;i++){ 71 hh(i); 72 Min=min(ss,Min); 73 } 74 printf("%d ",Min); 75 }