hdu 1598 find the most comfortable road

题目要求是可达情况下，舒适度最好，即速度之差最小。

1.因为不考虑距离 所以只要在同一集合中即可

2.需要在条件1下枚举最小速度，然后找符合条件的

 

 1 #include "iostream"

 2 #include "algorithm"

 3 #include "memory.h"

 4 #include "cmath"

 5 #include "string"

 6 #include "vector"

 7 #include "algorithm"

 8 #include "climits"

 9 using namespace std;

10 #define MAXN 1111

11 #define _min(a,b) (((a)<(b))?(a):(b))

12 struct node {

13     int x, y,speed;

14     bool operator < (node a) const{

15         return speed < a.speed;

16     }

17 }p[MAXN];

18 int fa[MAXN];

19 int n, m, q, t;

20 int re, num, ans;

21 

22 int find(int x)

23 {

24     if (fa[x] < 0) return x;

25     return fa[x] = find(fa[x]);

26 }

27 

28 void merge(int a, int b)

29 {

30     int x = find(a);

31     int y = find(b);

32     if (x < y) {

33         fa[x] += fa[y];

34         fa[y] = x;

35     }

36     if (x > y) {

37         fa[y] += fa[x];

38         fa[x] = y;

39     }

40 }

41 

42 

43 int main()

44 {

45     ios::sync_with_stdio(false);

46     while (cin >> n >> m) {

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

48             cin >> p[i].x >> p[i].y >> p[i].speed;

49         }

50         sort(p,p+m);

51         cin >> q;

52         for (int i = 0; i < q; ++i) {

53             int u, v;

54             cin >> u >> v;

55             ans = INT_MAX;

56             for (int j = 0; j < m; ++j) {

57                 memset(fa,-1,sizeof(fa));

58                 for (int k = j; k < m; ++k) {

59                     merge(p[k].x,p[k].y);

60                     if (find(u) == find(v)) {

61                         ans = _min(ans, p[k].speed - p[j].speed);

62                         break;

63                     }

64                 }

65             }

66             if (ans == INT_MAX) cout << "-1" << endl;

67             else cout << ans << endl;

68         }

69     }

70     return 0;

71 }