next unless exists $tree->{ $_ };

##</code><code>##

[17:25:23.81] C:\test>type hdb.dict
exactest
one
two
three
four
five
six
seven
eight
nine
ten
torewhen

[17:25:47.91] C:\test>1056884-calc hdb.dict
0.00380706787109375

[5] eehnortw : torewhen three one two ten
[1] aceesttx : exactest