题解 | 魔法相册的重复记忆

#include <iostream>
#include <algorithm>
#include <vector>
#include <map>
#include <set>
using namespace std;

int main() {
    int n;
    cin>>n;
    
    map<int,int> id_time;
    map<int,int> id_num;
    map<int,set<int>> id_appear;

    int id,t;
    for(int i=0;i<n;i++){
        while(cin>>id>>t){
            id_time[id]=t;
            id_num[id]++;
            id_appear[id].insert(i);

            if (cin.peek() == '\n') { //看下一位
                cin.get();  // 吃掉换行符
                break;      // 跳出while，进入下一个i
            }
        }
    }

    vector<pair<int,int>> ans; 
    for (auto& entry : id_num) {
        int id = entry.first;
        if (id_appear[id].size() > 1) {
            ans.push_back(pair<int, int>(id_time[id], id));
        }
    }

    sort(ans.begin(), ans.end());

    for (size_t i = 0; i < ans.size(); i++) {
        cout << ans[i].second << " " << id_num[ans[i].second] << " ";
    }
    cout << endl;
    
    return 0;
}