【Kruskal】P1991 无线通讯网

 1 #include<iostream>
 2 #include<algorithm>
 3 #include<cmath>
 4 #include<iomanip>
 5 using namespace std;
 6 
 7 int fa[501];
 8 
 9 int find(int x)
10 {
11     if (x == fa[x]) return x;
12     fa[x] = find(fa[x]);
13     return fa[x];
14 }
15 
16 struct Edge
17 {
18     int u;
19     int v;
20     double w;
21     bool operator <(Edge s)
22     {
23         return w < s.w;
24     }
25 }e[300010];
26 
27 int n, lim;
28 int cnt;
29 pair<int, int>node[501];
30 
31 int main()
32 {
33     cin >> lim >> n;
34     for (int i = 1; i <= n; i++)
35     {
36         fa[i] = i;
37         cin >> node[i].first >> node[i].second;
38     }
39     for (int i = 1; i <= n; i++)
40     {
41         for (int j = i + 1; j <= n; j++)
42         {
43             double dis = sqrt(pow(node[i].first - node[j].first, 2) + pow(node[i].second - node[j].second, 2));
44             e[++cnt].w = dis;
45             e[cnt].u = i;
46             e[cnt].v = j;
47         }
48     }
49     sort(e + 1, e + cnt + 1);
50     int tot = 1;
51     double maxd = -1;
52     lim = n - lim;
53     for (int i = 1; i <= cnt && lim; i++)
54     {
55         if (find(e[i].u) != find(e[i].v))
56         {
57             fa[find(e[i].u)] = e[i].v;
58             maxd = max(maxd, e[i].w);
59             lim--;
60         }
61     }
62     cout << fixed << setprecision(2) << maxd;
63 }
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posted on 2019-10-09 13:36 thjkhdf12 阅读(112) 评论(0) 收藏举报