poj1258 Agri-Net（Prime || Kruskal）

 1 #include <algorithm>
 2 #include <iostream>
 3 #include <cstring>
 4 #include <cstdio>
 5 using namespace std;
 6 
 7 const int INF = 0x7fffffff;
 8 const int N = 100 + 10;
 9 int map[N][N];
10 int dist[N];
11 int n;
12 
13 void prime()
14 {
15     int min_edge, min_node;
16     for (int i = 0; i < n; i++)
17         dist[i] = INF;
18     int ans = 0;
19     int now = 0;
20     for (int i = 0; i < n - 1; i++)
21     {
22         dist[now] = -1;
23         min_edge = INF;
24         for (int j = 0; j < n; j++)
25         {
26             if (j != now && dist[j] >= 0)
27             {
28                 if (map[now][j]>0)
29                     dist[j] = min(dist[j], map[now][j]);
30                 if (dist[j] < min_edge)
31                 {
32                     min_edge = dist[j];    //min_edge存储与当前结点相连的最短的边
33                     min_node = j;
34                 }
35             }
36         }
37         ans += min_edge;
38         now = min_node;
39     }
40     printf("%d\n", ans);
41 }
42 
43 int main()
44 {
45     //freopen("poj1258.txt", "r", stdin);
46     while (scanf("%d", &n) == 1)
47     {
48         memset(map, 0, sizeof(map));    //注意初始化
49         for (int i = 0; i < n; i++)
50             for (int j = 0; j < n; j++)
51                 cin >> map[i][j];
52         prime();
53     }
54     return 0;
55 }

 1 #include <algorithm>
 2 #include <iostream>
 3 #include <cstring>
 4 #include <cstdio>
 5 #include <vector>
 6 using namespace std;
 7 
 8 struct Edge
 9 {
10     int a, b, dist;
11 
12     Edge() {}
13     Edge(int a, int b, int d) :a(a), b(b), dist(d) {}
14 };
15 
16 bool cmp(Edge e1, Edge e2)
17 {
18     return e1.dist < e2.dist;
19 }
20 
21 const int N = 100 + 10;
22 vector<Edge> v;
23 int p[N];
24 int map[N][N];
25 int n;
26 
27 int find_root(int x)
28 {
29     if (p[x] == -1)
30         return x;
31     else return find_root(p[x]);
32 }
33 
34 void kruskal()
35 {
36     memset(p, -1, sizeof(p));
37     sort(v.begin(), v.end(), cmp);    //将边按边长从短到长排序
38     int ans = 0;
39     for (int i = 0; i < v.size(); i++)
40     {
41         int ra = find_root(v[i].a);
42         int rb = find_root(v[i].b);
43         if (ra != rb)
44         {
45             ans += v[i].dist;
46             p[ra] = rb;
47         }
48     }
49     printf("%d\n", ans);
50 }
51 
52 int main()
53 {
54     //freopen("poj1258.txt", "r", stdin);
55     while (scanf("%d", &n) == 1)
56     {
57         v.clear();    //注意初始化
58         for (int i = 0; i < n; i++)
59             for (int j = 0; j < n; j++)
60                 cin >> map[i][j];
61         for (int i = 0; i < n; i++)
62             for (int j = 0; j < n; j++)
63                 if (i < j) v.push_back(Edge(i, j, map[i][j]));
64         kruskal();
65     }
66     return 0;
67 }