HDU1213最简单的并查集问题

 1 #include<iostream>
 2 using namespace std;
 3 #define MAX 100005
 4 int fa[MAX];
 5 
 6 int findHead(int x)
 7 {
 8     while(x!=fa[x])
 9         x=fa[x];
10     return x;
11 }
12 
13 void Union(int x,int y)
14 {
15     int fa_x=findHead(x);
16     int fa_y=findHead(y);
17     if(fa_x!=fa_y) fa[fa_x]=fa_y;
18 }
19 
20 int main()
21 {
22     int T,N,M,A,B,count;
23     cin>>T;
24     while(T--){
25         count=0;
26         cin>>N>>M;
27         for(int j=1;j<=N;j++) fa[j]=j;
28         for(int i=0;i<M;i++){
29             cin>>A>>B;
30             Union(A,B);
31         }
32         for(int i=1;i<=N;i++)
33             if(fa[i]==i) count++;
34         cout<<count<<endl;
35     }
36     return 0;
37 }