Application_logs.cpp

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

vector<string> processLogs(vector<string> logs, int threshold) {
  map<int, int> mp; 
  for(auto x: logs) {
    
    int sp1 = -1, sp2 = -1;
    for(int i = 0; i < x.size(); ++i) {
      if(x[i] == ' ') {
        if(sp1 == -1) sp1 = i;
        else sp2 = i;
      } 
    }  
    int from = stoi(x.substr(0, sp1));
    int to = stoi(x.substr(sp1 + 1, sp2 - sp1 - 1));
    // cout << from << " " << to << " " << endl;
    // increse count for different users
    if(to == from) {
      mp[to]++;
    }
    else {
      mp[to]++;
      mp[from]++;
    }
  }
  vector<string> ans;
  
  for(auto x: mp) {
    if(x.second >= threshold) {
      ans.push_back(to_string(x.first));
    }
  }

  return ans;
}

int main() {
  
  int n, threshold;
  cin >> n;
  cin.ignore();
  vector<string> logs(n);
  for(int i = 0; i < n; ++i) {
    string temp;
    getline(cin, temp);
    logs[i] = temp;
  }
  cin >> threshold;
  
  vector<string> ans = processLogs(logs, threshold);
  
  for(auto s: ans) cout << s << endl;
}