题解 | 插队

#include <iostream>
#include <list>
#include <string>
#include <unordered_map>
using namespace std;

int main() {
    int n, m;
    cin >> n >> m;

    list<string> queue;
    unordered_map<string, list<string>::iterator> pos;
    string name, x, y;

    for (int i = 0; i < n; ++i) {
        cin >> name;
        queue.push_back(name);
        pos[name] = prev(queue.end());
    }

    for (int i = 0; i < m; ++i) {
        cin >> x >> y;

        auto it_x = pos[x];
        auto it_y = pos[y];

        if (it_x != it_y) {
            queue.erase(it_x);
            pos[x] = queue.insert(it_y, x);
        }
    }

    for (const string& name : queue) {
        cout << name << " ";
    }

    return 0;
}