【HDU1301】Jungle Roads（MST基础题）

爽爆。史上个人最快MST的记录7分40s。。一次A。

 

 1 #include <iostream>

 2 #include <cstring>

 3 #include <cstdlib>

 4 #include <cstdio>

 5 #include <cmath>

 6 #include <cctype>

 7 #include <algorithm>

 8 #include <numeric>

 9 

10 #define typec int

11 using namespace std;

12 

13 const typec inf = 0xffff;

14 const int V = 35;

15 int vis[V]; typec lowc[V];

16 int Map[V][V];

17 

18 typec prim (typec cost[][V], int n) {

19     int i, j, p;

20     typec minc, res = 0;

21     memset(vis, 0, sizeof (vis));

22     vis[0] = 1;

23     for (i = 1; i < n; ++ i) lowc[i] = cost[0][i];

24     for (i = 1; i < n; ++ i) {

25         minc = inf; p = -1;

26         for (j = 0 ; j < n; ++ j) {

27             if ( 0 == vis[j] && minc > lowc[j]) {

28                 minc = lowc[j]; p = j;

29             }

30         }

31         if (inf == minc) return -1;

32         res += minc; vis[p] = 1;

33         for (j = 0 ; j < n; ++ j) {

34             if (0 == vis[j] && lowc[j] > cost[p][j]) {

35                 lowc[j] = cost[p][j];

36             }

37         }

38     }

39     return res;

40 }

41 

42 

43 int main () {

44     int n;

45     while (~scanf("%d", &n)) {

46         if (n == 0) break;

47         for (int i = 0 ; i < n; ++ i) {

48             for (int j = 0 ;j < n; ++ j) {

49                 if (i == j) Map[i][j] = 0;

50                 else Map[i][j] = inf;

51             }

52         }

53 

54         for (int i = 0 ; i < n - 1; ++ i) {

55             char s_c; int e_n;

56             cin >> s_c >> e_n;

57             for (int j = 0 ; j < e_n; ++ j) {

58                 char e_c; int w;

59                 cin >> e_c >> w;

60                 Map[s_c - 'A'][e_c - 'A'] = Map[e_c - 'A'][s_c - 'A'] = min(Map[s_c - 'A'][e_c - 'A'], w);

61             }

62         }

63 

64         cout << prim(Map, n) << endl;

65     }

66     return 0;

67 }