Switches with codes and opening a door

[slickdeath97]

I am looking to make an event where a door will only open if switches are hit in the right order. How would I go at doing this without a lot of Control switches and control variables? Do note the best example I can come up with is making a button coded door in minecraft if that helps. Thanks for the help.

 

[ShadowDragon]

watch this video where he make a bridge appear, the same thing can be done using
a door or something else.