Re: How to walkthrough a tree and calculate value on path?

[gyorokpeter-kx]

This gets it done while remaining somewhat readable:

child:select (child,'data) by parent from tree; 
res:(); 
a:([]start:key[child];end:key[child];val:1); 
while[count a; res,:select from a where not end in key child; b:ungroup update nxt:child end from (delete from a where not end in key child); a:select start, end:nxt[;0], val*nxt[;1] from b; ];

The answer is given by

q)`start`end xasc res 
start end val 
------------- 
A     C   2 
A     D   3 
A     F   5 
A     G   24 
A     H   28 
B     F   5 
B     G   24 
B     H   28 
E     G   6 
E     H   7