并查集 路径压缩 模板

ACWING 837. 连通块中点的数量

#include <bits/stdc++.h>
using namespace std;
const int N = 100005;

int p[N], siz[N];  //只有根节点的size是有意义的

inline int find(int x) 
{
   
    if (p[x] != x) p[x] = find(p[x]);    //路径压缩

    return p[x];
}

int main() 
{
   
#ifndef ONLINE_JUDGE
    freopen("D:/VS CODE/C++/in.txt", "r", stdin);
    freopen("D:/VS CODE/C++/out.txt", "w", stdout);
#endif
    int n, m;
    cin >> n >> m;

    for (int i = 1; i <= n; ++i) {
   
        p[i] = i;
        siz[i] = 1;
    }

    char op[3];
    while (m -- ) {
   
        scanf("%s", &op);
        if (op[0] == 'C') {
   
            int a, b;
            cin >> a >> b;
    
            if (find(a) == find(b)) continue;
            else {
   
                siz[find(b)] += siz[find(a)];
                p[find(a)] = find(b);
            }
        }
        else if (op[0] == 'Q' and op[1] == '1') {
   
            int a, b;
            cin >> a >> b;

            if (find(a) == find(b))
                cout << "Yes" <<endl;
            else
                cout << "No" << endl;
        }
        else {
   
            int a;
            cin >> a;

            cout << siz[find(a)] << endl;
        }
    }

    fclose(stdin);
    fclose(stdout);
    return 0;
}