algorithm - What is the best way to sort a partially ordered list? -

Probably best illustrated with a short example.
Looking at the relationship

  a < B & L; C & LT; P & LT; Q  

will be the correct output

  ABCPQ or APKBC or APBCcu ... etc  

In other words

I am most interested in the solution which is the easiest to implement, but also in speed and time in the best o (n) Interesting.

P>

It is called.

The standard algorithm is to output the minimum element, then remove it and repeat until done.