hdoj1102 Constructing Roads（Prime || Kruskal）

 1 #include <algorithm>
 2 #include <cstring>
 3 #include <cstdio>
 4 using namespace std;
 5 
 6 const int INF = 0x7fffffff;
 7 const int N = 100 + 10;
 8 int map[N][N];
 9 int dist[N];    //记录从起点到其余各点的长度，不断更新
10 int n, q;
11 
12 void prime()
13 {
14     int min_edge, min_node;
15     for (int i = 1; i <= n; i++)
16         dist[i] = INF;
17     int ans = 0;
18     int now = 1;
19     for (int i = 1; i < n;i++)
20     {
21         min_edge = INF;
22         dist[now] = -1;
23         for (int j = 1; j <= n; j++)
24         {
25             if (j != now && dist[j] >= 0)    //注意是dist[j]>=0
26             {
27                 if (map[now][j] >= 0)
28                     dist[j] = min(dist[j], map[now][j]);
29                 if (dist[j] < min_edge)
30                 {
31                     min_edge = dist[j];    ////min_edge存储与当前结点相连的最短的边
32                     min_node = j;
33                 }
34             }
35         }
36         ans += min_edge;    ////ans存储最小生成树的长度
37         now = min_node;
38     }
39     printf("%d\n", ans);
40 }
41 
42 int main()
43 {
44     //freopen("hdoj1102.txt", "r", stdin);
45     while (scanf("%d", &n) == 1)
46     {
47         memset(map, 0, sizeof(map));
48         for (int i = 1; i <= n;i++)
49             for (int j = 1; j <= n; j++)
50                 scanf("%d", &map[i][j]);
51         scanf("%d", &q);
52         int a, b;
53         for (int i = 0; i < q; i++)
54         {
55             scanf("%d%d", &a, &b);
56             map[a][b] = map[b][a] = 0;
57         }
58         prime();
59     }
60     return 0;
61 }

 1 #include <algorithm>
 2 #include <cstring>
 3 #include <cstdio>
 4 #include <vector>
 5 using namespace std;
 6 
 7 struct Edge
 8 {
 9     int a, b, dist;
10 
11     Edge() {}
12     Edge(int a, int b, int d) :a(a), b(b), dist(d) {}
13     bool operator < (Edge edge)    //将边按边长从短到长排序
14     {
15         return dist < edge.dist;
16     }
17 };
18 
19 const int N = 100 + 10;
20 int p[N];    //并查集使用
21 int map[N][N];
22 vector<Edge> v;
23 int n, q;
24 
25 int find_root(int x)
26 {
27     if (p[x] == -1)
28         return x;
29     else return find_root(p[x]);
30 }
31 
32 void kruskal()
33 {
34     memset(p, -1, sizeof(p));
35     sort(v.begin(), v.end());
36     int ans = 0;
37     for (int i = 0; i < v.size(); i++)
38     {
39         int ra = find_root(v[i].a);
40         int rb = find_root(v[i].b);
41         if (ra != rb)
42         {
43             ans += v[i].dist;
44             p[ra] = rb;
45         }
46     }
47     printf("%d\n", ans);
48 }
49 
50 int main()
51 {
52     //freopen("hdoj1102.txt", "r", stdin);
53     while (scanf("%d", &n) == 1)
54     {
55         v.clear();
56         int t;
57         for (int i = 1; i <= n; i++)
58             for (int j = 1; j <= n; j++)
59                 scanf("%d", &map[i][j]);
60         scanf("%d", &q);
61         int a, b;
62         for (int i = 0; i < q; i++)
63         {
64             scanf("%d%d", &a, &b);
65             map[a][b] = map[b][a] = 0;
66         }
67 
68         for (int i = 1; i <= n; i++)
69             for (int j = 1; j <= n; j++)
70                 if (j > i)    v.push_back(Edge(i, j, map[i][j]));
71 
72         kruskal();
73     }
74     return 0;
75 }