isIsogram
| i |
i := 0.
self asLowercase do: [ :char |
| val |
val := (char asInteger - 96).
(val between: 1 and: 26) ifFalse: [ ^ false ].
(i bitAt: val ) == 1 ifTrue: [ ^ false ].
i bitAt: val put: 1
].
^ true
An interesting observation here is that if #asLowercase is moved to each
character instead “val := (char asLowercase asInteger - 96).” Then it leads to
a 4-5x performance loss .
From: Pharo-users [mailto:pharo-users-boun...@lists.pharo.org] On Behalf Of
Damien Pollet
Sent: Friday, November 11, 2016 4:14 PM
To: Any question about pharo is welcome <pharo-users@lists.pharo.org>
Subject: Re: [Pharo-users] Little challenges for a friday evening
On 11 November 2016 at 12:02, stepharo
<steph...@free.fr<mailto:steph...@free.fr>> wrote:
String>>#isIsogram
| letters |
letters := Dictionary new.
self do: [ :x | letters at: x ifAbsent: [] ifPresent: [ ^false ].
Yes I did that one too and I was surprised because it was as slow as the bag
implementation.
Anyone tried replacing the dictionary with an array of 26 booleans and indexing
based on ascii, or even a SmallInteger and bit shifting?
