James questions

• Is there a controllable way to slow down my C++ program on online judges?
• Is it possible to reuse variable names with using namespace?
• May I clear a priority_queue by clearing its underlying container?
• Inserting to std::unordered_map calls hash function twice in MSVC++'s STL, bad design or special reason?
• Error:"invalid comparator" when sorting using custom comparison function

James answers