【HDU1162】Eddy's picture（MST基础题）

很基础的点坐标MST，一不留神就AC了， - - ！！

 

 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 #include <limits.h>

10 

11 #define typec double

12 using namespace std;

13 

14 const int inf = 0xffff;

15 const int V = 105;

16 int vis[V];

17 typec lowc[V], Map[V][V], point[V][2];

18 

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

20     int i, j, p;

21     typec minc, res = 0;

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

23     vis[0] = 1;

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

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

26         minc = inf;

27         p = -1;

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

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

30                 minc = lowc[j];

31                 p = j;

32             }

33         }

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

35         res += minc;

36         vis[p] = 1;

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

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

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

40             }

41         }

42     }

43     return res;

44 }

45 

46 double cal_dis (double x1, double y1, double x2, double y2) {

47     return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));

48 }

49 

50 int main () {

51     int n;

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

53 

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

55             scanf("%lf %lf", &point[i][0], &point[i][1]);

56         }

57 

58         for (int i = 0 ; i < V; ++ i) {

59             for (int j = 0; j < V; ++ j) {

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

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

62             }

63         }

64 

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

66             for (int j = i + 1; j < n; ++ j) {

67                 Map[i][j] = Map[j][i] =

68                     cal_dis(point[i][0], point[i][1], point[j][0], point[j][1]);

69             }

70         }

71 

72         //cout << prim(Map, n) << endl;

73         printf("%.2lf\n", prim(Map, n));

74     }

75     return 0;

76 }