hdu 2818 Building Block 种类并查集

在进行并的时候不能瞎jb并，比如（x, y）就必须把x并给y ,即fa[x] = y

 #include <iostream>
 #include <string>
 #include <cstring>
 #include <algorithm>
 using namespace std;

 const int maxn =  + ;
 int a[maxn];
 int fa[maxn];
 int Rank[maxn];
 int cnt[maxn];    //种类

 int Find(int x){
     if (x == fa[x])
         return x;
     int t = Find(fa[x]);
     cnt[x] += cnt[fa[x]];
     return fa[x] = t;
 }

 void init(){
     memset(cnt, , sizeof(cnt));
     for (int i = ; i < maxn; i++){
         fa[i] = i;
         Rank[i] = ;
     }
 }

 void set_union(int x, int y){
     int xx = Find(x);
     int yy = Find(y);
     if (xx == yy)
         return;
     fa[xx] = yy;
     cnt[xx] = Rank[yy];
     Rank[yy] += Rank[xx];
 }

 int main(){
     std::ios::sync_with_stdio(false);
     init();
     int t;
     cin >> t;
     while (t--){
         string s;
         int x, y;
         cin >> s;
         if (s == "M"){
             cin >> x >> y;
             set_union(x, y);
         }
         else{
             cin >> x;
             int t = Find(x);
             cout << cnt[x] << endl;
         }
     }
     //system("pause");
     return ;
 }