1595

#include<iostream>#include<vector>#include<string>#include<type_traits>#include<sstream>#include<tuple>#include<bitset>#include<regex>#include<set>#include<queue>#include<map>using namespace std;bool compare(pair<int,int> a,pair<int,int> b){if (a.first == b.first) return a.second < b.second;return a.first < b.first;}int main(){int T;cin >> T;int N;while (T--){cin >> N;vector<pair<int, int>> point;set<pair<int, int>> search;double ave_x=0;for (int i = 0; i < N; i++){pair<int, int> temp;cin >> temp.first >> temp.second;ave_x += temp.first;point.push_back(temp);search.insert(temp);}sort(point.begin(),point.end(),compare);ave_x /= N;bool flag = true;for (int i = 0; i < N; i++){pair<int, int> temp = point[i];pair<int, int> temp1;temp1.second = temp.second;temp1.first = 2 * ave_x - temp.first;if (search.find(temp1) == search.end()){cout << "NO" << endl;flag = false;break;}}if (flag) cout << "YES" << endl;}//system("pause");return 0;}