Prioritization function needed (recursive help!)

[rh0dium]

Hi all,

I need some help on writing a recursive priority function

Given a list = [ A, B, C, D]

Where the following constraints are in place:

A depends on [B, C]
C depends on

Figure out real order that prioritizes these.

Output [ B, C, A, D ] is valid. (Actually D could be anywhere in it
as it doesn't matter..)

I am really struggling on simply how to organize the data and write
the corresponding function - I tried classes but I don't know if
that's the best approach. See my other post on this.

Thanks

 

[Paul Rubin]

I am really struggling on simply how to organize the data and write
the corresponding function - I tried classes but I don't know if
that's the best approach. See my other post on this.

We just had a discussion thread about this. Is it a homework problem?

Anyway, look up "topological sorting" in a CS textbook or on Wikipedia.

 

[Arnaud Delobelle]

Hi all,

I need some help on writing a recursive priority function

Given a list = [ A, B, C, D]

Where the following constraints are in place:

A depends on [B, C]
C depends on

Figure out real order that prioritizes these.

Output [ B, C, A, D ] is valid.  (Actually D could be anywhere in it
as it doesn't matter..)

I am really struggling on simply how to organize the data and write
the corresponding function - I tried classes but I don't know if
that's the best approach.  See my other post on this.

Thanks

There's a very recent thread on this subject (topological sort)

 

[Kent Johnson]

Hi all,

I need some help on writing a recursive priority function

Given a list = [ A, B, C, D]

Where the following constraints are in place:

A depends on [B, C]
C depends on

Figure out real order that prioritizes these.

You need a topological sort.
http://en.wikipedia.org/wiki/Topological_sort

Two Python implementations:
http://pypi.python.org/pypi/topsort/0.9
http://www.bitformation.com/art/python_toposort.html

Kent