51Nod 1212 无向图最小生成树

Posted 2020-10-29 jaydenouyang

 1 //克鲁斯卡尔
 2 #include <iostream>
 3 #include <algorithm>
 4 
 5 using namespace std;
 6 const int maxn = 50000 + 5;
 7 
 8 struct node{
 9     int x, y;
10     int len;
11 }g[maxn];
12 
13 bool cmp(node x, node  y){
14     return x.len < y.len;
15 }
16 
17 int fa[maxn];
18 
19 int Find(int x){
20     if (x == fa[x])
21         return x;
22     else
23         return fa[x] = Find(fa[x]);
24 }
25 
26 
27 int main(){
28     ios::sync_with_stdio(false);
29 
30     int n, m;
31     cin >> n >> m;
32     for (int i = 0; i <= n; i++){
33         fa[i] = i;
34     }
35 
36     int a, b, c;
37     for (int i = 0; i < m; i++){
38         cin >> a >> b >> c;
39         g[i].x = a;
40         g[i].y = b;
41         g[i].len = c;
42     }
43     int ans = 0;
44     sort(g, g + m, cmp);
45     for (int i = 0; i < m; i++){
46         int u, v;
47         u = g[i].x;
48         v = g[i].y;
49         int u1 = Find(u);
50         int v1 = Find(v);
51         if (u1 != v1){
52             fa[v1] = u1;
53             ans += g[i].len;
54         }
55     }
56     cout << ans << endl;
57     return 0;
58 }