Poj2485--Highways

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <iostream>
 4 using namespace std;
 5 
 6 const int INF = 0x3f3f3f3f;
 7 int map[550][550], dis[550]; bool vis[550];
 8 int n;
 9 
10 void Prim()
11 {
12     memset(vis, true, sizeof(vis));
13     for(int i = 1; i <= n; i++)
14         dis[i] = map[1][i];
15     vis[1] = false; int  max = -INF;
16     for(int i = 1; i < n; i++)
17     {
18         int temp, min = INF;
19         for(int j = 1; j <= n; j++)          //寻找吓一条you最小权值边。 
20         {
21             if(vis[j] && dis[j] < min)
22             {
23                 temp = j;     
24                 min = dis[j];
25             }
26         }
27         if(min > max)  
28             max = min;
29         vis[temp] = false;
30         for(int j = 1; j <= n; j++)          //更新的是 ? ? 
31             if(vis[j] && dis[j] > map[temp][j])
32                 dis[j] = map[temp][j];
33     }
34     printf("%d\n", max);
35 }
36 int main()
37 {
38     int t;
39     scanf("%d", &t);
40     while(t--)
41     {
42         scanf("%d", &n);
43         for(int i = 1; i <= n; i++)
44             for(int j = 1; j <= n; j++)
45                 cin >> map[i][j];
46         Prim();
47     }
48     return 0;
49 }

 1 #include <cmath>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <iostream>
 5 #include <algorithm>
 6 using namespace std;
 7 
 8 const int INF = 0x3f3f3f3f;
 9 int map[550][550], father[550];
10 int n;
11 struct rode
12 {
13     int a, b, w;     
14 } num[250000];
15 
16 bool cmp(rode a, rode b)
17 {
18     return a.w < b.w;     
19 }
20 
21 void init()
22 {
23     for(int i = 1; i <= n; i++)
24         father[i] = i;
25 }
26 
27 int find(int a)
28 {
29     int r, j , k;
30     r = a;
31     while(r != father[r])
32         r = father[r];
33     j = a;
34     while(j != r)
35     {
36         k = father[j];
37         father[j] = r; 
38         j = k;    
39     }
40     return r; 
41 }
42 
43 bool mercy(int a, int b)
44 {
45     int q = find(a);
46     int p = find(b);
47     if(q != p)
48     {
49         father[q] = p;
50         return true;
51     }
52     else
53         return false;
54 }
55 
56 int main()
57 {
58     int t;
59     while(~scanf("%d", &t))
60     {
61         while(t--)
62         {
63             int k  = 0;
64             scanf("%d", &n);
65             init();
66             for(int i = 1; i <= n; i++)
67             for(int j = 1; j <= n; j++)
68             {
69                 cin >> map[i][j];
70                 if(i != j)
71                 {num[k].a = i; num[k].b = j; num[k++].w = map[i][j];}    
72             }    
73             sort(num, num+k, cmp);
74             int max = -INF;
75             for(int i = 0; i < k; i++)
76             {
77                 if(mercy(num[i].a, num[i].b))    
78                 {
79                     if(num[i].w > max)
80                         max = num[i].w; 
81                 }
82             }    
83             printf("%d\n", max);
84         }
85     }
86     return 0;    
87 }