Accelerate C ++ cin, cout speed

With the following two lines of code:

    :: sync_with_stdio iOS ( to false );    // acceleration 
    cin.tie ( 0 );

1. First SYNC_ WITH_ the stdio (to false) to interrupt the output to the input buffer iostream, can save a lot of time, so that almost the same with scanf.
2. The stream is a function of two tie binding, if an empty parameter returns the current output pointer, i.e. tie (0) and the tie (nullptr a) cin and cout to solve the binding.