标签：air end inpu via contain problem must route wal
题目链接：
https://vjudge.net/problem/POJ-3268
One cow from each of N farms (1 ≤ N ≤ 1000) conveniently numbered 1..N is going to attend the big cow party to be held at farm #X (1 ≤ X ≤ N). A total of M (1 ≤ M ≤ 100,000) unidirectional (one-way roads connects pairs of farms; road i requires Ti (1 ≤ Ti ≤ 100) units of time to traverse.
Each cow must walk to the party and, when the party is over, return to her farm. Each cow is lazy and thus picks an optimal route with the shortest time. A cow‘s return route might be different from her original route to the party since roads are one-way.
Of all the cows, what is the longest amount of time a cow must spend walking to the party and back?
4 8 2 1 2 4 1 3 2 1 4 7 2 1 1 2 3 5 3 1 2 3 4 4 4 2 3Sample Output
10Hint
1 /* 2 关键是反向存储，求最短路的思维转换 3 */ 4 #include<stdio.h> 5 #include<string.h> 6 #include<algorithm> 7 using namespace std; 8 void Dijkstra(int s,int e[][1010]); 9 #define inf 99999999 10 int dis[1010],book[1010],e[1010][1010],f[1010][1010],d[1010],n,m; 11 int main() 12 { 13 int i,j,k,x,a,b,c,maxn,temp; 14 while(scanf("%d%d%d",&n,&m,&x)!=EOF) 15 { 16 memset(d,0,sizeof(d)); 17 for(i=1;i<=n;i++) 18 for(j=1;j<=n;j++) 19 if(i==j) 20 { 21 e[i][j]=0; 22 f[i][j]=0; 23 } 24 else 25 { 26 e[i][j]=inf; 27 f[i][j]=inf; 28 } 29 30 for(i=1;i<=m;i++) 31 { 32 scanf("%d%d%d",&a,&b,&c); 33 if(c<e[a][b]) 34 { 35 e[a][b]=c; 36 f[b][a]=c; 37 } 38 } 39 Dijkstra(x,e);//回 40 Dijkstra(x,f);//去 41 maxn=-1; 42 for(i=1;i<=n;i++) 43 { 44 if(d[i]>maxn) 45 maxn=d[i]; 46 } 47 printf("%d\n",maxn); 48 } 49 return 0; 50 } 51 void Dijkstra(int s,int e[][1010]) 52 { 53 int i,j,k,min,u; 54 for(i=1;i<=n;i++) 55 dis[i]=e[s][i]; 56 memset(book,0,sizeof(book)); 57 book[s]=1; 58 for(k=1;k<n;k++) 59 { 60 min=inf; 61 for(i=1;i<=n;i++) 62 if(book[i]==0&&dis[i]<min) 63 { 64 min=dis[i]; 65 u=i; 66 } 67 book[u]=1; 68 for(i=1;i<=n;i++) 69 if(book[i]==0&&dis[i]>dis[u]+e[u][i]) 70 dis[i]=dis[u]+e[u][i]; 71 } 72 for(i=1;i<=n;i++) 73 d[i]+=dis[i]; 74 }
POJ 3268 Silver Cow Party（Dijkstra算法求解来回最短路问题）
标签：air end inpu via contain problem must route wal
原文地址：https://www.cnblogs.com/wenzhixin/p/9429531.html
