hdu1102 Constructing Roads 基础最小生成树

Posted 2020-09-29

 1 //克鲁斯卡尔（最小生成树）
 2 #include<cstdio>
 3 #include<iostream>
 4 #include<algorithm>
 5 using namespace std;
 6 
 7 const int maxn = 100005;
 8 int n, t;
 9 struct node
10 {
11     int bagin, end, len;
12 }arr[maxn];
13 int fa[maxn];
14 
15 void init()
16 {
17     for (int i = 0; i <= n; i++)
18     {
19         fa[i] = i;
20     }
21 }
22 
23 bool cmp(node a, node b)
24 {
25     return a.len<b.len;
26 }
27 
28 int find(int x)
29 {
30     if (x != fa[x])
31         fa[x] = find(fa[x]);
32     return fa[x];
33 }
34 
35 int main()
36 {
37     while (cin >> n)
38     {
39         t = 0;
40         for (int i = 1; i <= n; i++)
41         {
42             for (int j = 1; j <= n; j++)
43             {
44                 int x;
45                 cin >> x;
46                 arr[t].bagin = i; arr[t].end = j; arr[t].len = x;
47                 t++;
48             }
49         }
50         sort(arr, arr + t, cmp);
51         init();
52         int m;
53         cin >> m;
54         while (m--)
55         {
56             int a, b;
57             cin >> a >> b;
58             int fx, fy;
59             fx = find(a); fy = find(b);
60             fa[fy] = fx;
61         }
62         int ans = 0;
63         for (int i = 0; i<t; i++)
64         {
65             int fx, fy;
66             fx = find(arr[i].bagin);
67             fy = find(arr[i].end);
68             if (fx != fy)
69             {
70                 ans += arr[i].len;
71                 fa[fy] = fx;
72             }
73         }
74         cout << ans << endl;
75     }
76     return 0;
77 }