Task Asssignment

• Time : O(nlogn)
• Space : O(n)

vector<vector<int>> taskAssignment(int k, vector<int> tasks) {
	vector<pair<int,int>> vpi;
	for(int i = 0; i < 2*k; i++) {
		vpi.push_back({tasks[i],i});
	}
  sort(begin(vpi),end(vpi));
	vector<vector<int>> res;
	
	for(int i = 0, j = 2*k-1; i < k; i++,j--) {
		res.push_back({vpi[i].second, vpi[j].second});
	}
  return res;
}