poj 2387 Til the Cows Come Home(dijkstra算法)

题目链接：http://poj.org/problem?id=2387

题目大意：起点一定是1，终点给出，然后求出1到所给点的最短路径。

注意的是先输入边，在输入的顶点数，不要弄反哦~~~

 1 #include <iostream>

 2 #include <cstdio>

 3 using namespace std;

 4 int map[2010][2010],Min,node[2010],vis[2010],t,q;

 5 const int INF=9999999;

 6 

 7 void set()

 8 {

 9     for (int i=1; i<=2001; i++)

10     {

11         node[i]=INF;

12         vis[i]=0;

13         for (int j=1; j<=2001; j++)

14             map[i][j]=INF;

15     }

16 }

17 

18 int dijkstra(int m)

19 {

20     int tm=m;

21     vis[m]=1;

22     node[m]=0;

23     for (int k=2; k<=q; k++)

24     {

25         Min=INF;

26         for (int i=1; i<=q; i++)

27             if (!vis[i])

28             {

29                 if (node[i]>map[tm][i]+node[tm])

30                 {

31                     node[i]=map[tm][i]+node[tm];

32                     //cout<<map[tm][i]<<" "<<node[i]<<endl;

33                 }

34                 if (Min>node[i])

35                 {

36                     //cout<<Min<<endl;

37                     Min=node[i];

38                     m=i;

39                 }

40             }

41         vis[m]=1;

42         tm=m;

43     }

44     return Min;

45 }

46 

47 int main ()

48 {

49     int n;

50     //memset(map,0,sizeof(map));

51     while (~scanf("%d%d",&t,&n))

52     {

53         q=0;

54         set();

55         while (t--)

56         {

57             int a,b,c;

58             scanf("%d%d%d",&a,&b,&c);

59             if (q<a)

60                 q=a;

61             else if (q<b)

62                 q=b;

63             if (map[a][b]>c)

64             {

65                 map[a][b]=map[b][a]=c;

66             }

67         }

68         dijkstra(n);

69         printf("%d\n",node[1]);

70     }

71     return 0;

72 }