并查集，用map映射下，然后记得记录父亲

cpp
#include <cstdio>
#include <iostream>
#include <map>
using namespace std;



map<string, string> p;

string find(string x) {
    if (x != p[x]) 
        p[x] = find(p[x]);
    return p[x];
}

string s, s1;

int main() {
    char ch;
    cin >> ch;
    while (ch != '$') {
        cin >> s;
        if (ch == '#') {
            s1 = s;
            if (p[s] == "") p[s] = s;
        } else if (ch == '+') {
            p[s] = s1;
        } else {
            cout << s << ' ' << find(s) << endl;
        }
        cin >> ch;
    }
    return 0;
}