hdu1874畅通工程续
http://acm.hdu.edu.cn/showproblem.php?pid=1874
floyd: 62MS
View Code
1 #include<iostream> 2 using namespace std ; 3 #define maxn 210 4 const int oo = 1<<28 ; 5 int map[maxn][maxn] ; 6 int n ; 7 void init() 8 { 9 for(int i=0; i<n; i++) 10 for(int j=0; j<n; j++) 11 { 12 map[i][j] = oo ; 13 if(i==j) 14 map[i][j] = 0 ; 15 } 16 } 17 void floyd() 18 { 19 for(int k=0; k<n; k++) 20 for(int i=0; i<n; i++) 21 for(int j=0; j<n; j++) 22 if(map[i][j]>map[i][k]+ map[k][j]) 23 map[i][j] = map[i][k] + map[k][j] ; 24 } 25 int main() 26 { 27 int m, a, b, c, s, t ; 28 while(cin>>n>>m) 29 { 30 init() ; 31 while(m--) 32 { 33 cin>>a>>b>>c ; 34 if(map[a][b]>c) 35 map[a][b] = map[b][a] = c ; 36 } 37 cin>>s>>t ; 38 floyd() ; 39 if(map[s][t]<oo) 40 cout<<map[s][t]<<endl ; 41 else 42 cout<<"-1"<<endl ; 43 } 44 return 0 ; 45 }
dijkstra: 15MS
View Code
1 #include<iostream> 2 #include<map> 3 #include<cstdio> 4 #include<cstring> 5 #include<string> 6 #include<algorithm> 7 using namespace std; 8 9 #define MAX 0x3f3f3f3f 10 #define N 210 11 int num, road, dis[N], len[N][N]; 12 bool visit[N]; 13 14 15 void Dijkstra(int start) 16 { 17 int k, temp; 18 memset(visit, 0, sizeof(visit)); 19 for(int i = 0; i < num; ++i) //初始化 20 dis[i] = (i==start ? 0 : MAX); 21 for(int i = 0; i < num; ++i) 22 { 23 temp = MAX; 24 for(int j = 0; j < num; ++j) //查找最短路 25 if(!visit[j] && dis[j] < temp) 26 temp = dis[k = j]; 27 visit[k] = 1; 28 for(int j = 0; j < num; ++j) //更新源点到其他点的最短路 29 if(!visit[j] && dis[j] > dis[k] + len[k][j]) 30 dis[j] = dis[k] + len[k][j]; 31 } 32 } 33 34 int main() 35 { 36 int a, b, cost, start, end; 37 while(scanf("%d%d", &num, &road) != EOF) 38 { 39 memset(len, MAX, sizeof(len)); 40 for(int i = 0; i < road; ++i) 41 { 42 scanf("%d%d%d", &a, &b, &cost); 43 if(cost < len[a][b]) //一条路可以有多个cost，记录最小的。注意~~~ 44 len[a][b] = len[b][a] = cost; 45 } 46 scanf("%d%d", &start, &end); 47 Dijkstra(start); 48 if(dis[end] == MAX) printf("-1\n"); 49 else printf("%d\n", dis[end]); 50 } 51 return 0; 52 }
