http://www.mokit.top/problem/program/3310

c++代码

#include <bits/stdc++.h>
using namespace std;

#define endl '\n'
#define fx first
#define fy second
#define LL long long
#define ph push_back
#define INF 0x3f3f3f3f
#define PII pair<int,int>

const int N = 3e4 + 5;

int p[N], sz[N], d[N];

int find(int x) {
    if (p[x] != x) {
        int root = find(p[x]);
        d[x] += d[p[x]];
        p[x] = root;
    }
    return p[x];
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    for (int i = 1; i < N; i ++) sz[i] = 1, p[i] = i;

    int t; cin >> t;
    while (t --) {
        char op; cin >> op;
        int a, b;
        if (op == 'M') {
            cin >> a >> b;
            int pa = find(a), pb = find(b);
            d[pb] = sz[pa];
            sz[pa] += sz[pb];
            p[pb] = pa;
        }
        else {
            cin >> a;
            int pa = find(a);
            cout << max(0, sz[pa] - d[a] - 1) << endl;
        }
    }
    return 0;
}