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 = 30000 + 5;
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, 0, sizeof(cnt));
    for (int i = 0; i < maxn; i++){
        fa[i] = i;
        Rank[i] = 1;
    }
}


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 0;
}