# Numbering levels of a tree [closed]

I find the need to use an explicit level numbering for a tree. i.e. in the tree:

    A
/ \
B   B
/\   /\
C  C C  C


should I number the level C the 3rd and A as the first, or the opposite? As going 'up' the tree is going towards A; should the numbering reflect that as well? If can, please supply an authorized CS reference.

Thanks!

• You don't say what you need the numbering for, so how can anyone say which numbering is "best"? – Raphael Nov 17 '14 at 18:04
• If there is no consensus on level numbering, this is a good answer as well. – Jaaz Nov 18 '14 at 11:24