并查集

1. 将n个元素进行映射，对应n个数字(节点)
2. 每个元素的初始祖先(树根节点)都是自己
3. find函数找对是x节点的根节点
4. 每次合并，都是将两颗树的树根节点进行合并，其中一个根节点变成另一个点儿子节点

#include <iostream>
#include <cstdio>
#include <algorithm>
using namespace std;
const int N = 100010;
int a[N], f[N];
int n, m;

int find(int x) {
    if (f[x] == x) return x;
    return f[x] = find(f[x]);
}

void merge(int a, int b){
    int x = find(a), y = find(b);
    if (x == y) return;
    f[x] = y;
}

int query(int a, int b) {
    return find(a) == find(b);
}

int main() {
    cin >> n >> m;
    for (int i = 1; i <= n; i++) f[i] = i;
    for (int i = 0; i < m; i++) {
        char a;
        int x, y;
        cin >> a >> x >> y;
        if (a == 'M') merge(x, y);
        else {
            if (query(x, y)) cout << "Yes" << endl;
            else cout << "No" << endl;
        }
    }
    return 0;
}