hdu--4424--并查集

 1 #include <iostream>
 2 #include <cstring>
 3 using namespace std;
 4 
 5 typedef __int64 LL;
 6 LL n;
 7 const int size = 200010;
 8 
 9 LL dist[size];
10 LL father[size] , rank[size];
11 struct data
12 {
13     LL u , v , w;
14     bool operator < ( const data& p ) const
15     {
16         return w > p.w;
17     }
18 }node[size];
19 
20 void init( )
21 {
22     memset( dist , 0 , sizeof(dist) );
23     for( int i = 0 ; i<=n ; i++ )
24     {
25         father[i] = i;
26         rank[i] = 1;
27     }
28 }
29 
30 LL find( LL x )
31 {
32     return father[x] == x ? x : father[x] = find( father[x] );
33 }
34 
35 void Union( LL x , LL y , LL len )//将y集合并到x集合中
36 {
37     father[y] = x;
38     rank[x] += rank[y];
39     dist[x] = len;
40 }
41 
42 void solve( )
43 {
44     for( int i = 0 ; i<n-1 ; i++ )
45     {
46         LL x = find( node[i].u );
47         LL y = find( node[i].v );
48         LL len1 = dist[x] + rank[y] * node[i].w;
49         LL len2 = dist[y] + + rank[x] * node[i].w;
50         if( len1>=len2 )
51         {
52             Union( x , y , len1 );
53         }
54         else
55         {
56             Union( y , x , len2 );
57         }
58     }
59 }
60 
61 int main()
62 {
63     cin.sync_with_stdio(false);
64     while( cin >> n )
65     {
66         init( );
67         for( int i = 0 ; i<n-1 ; i++ )
68         {
69             cin >> node[i].u >> node[i].v >> node[i].w;
70         }
71         sort( node , node+n-1 );
72         solve( );
73         cout << dist[ find(1) ] << endl;
74     }
75     return 0;
76 }