A ><>>>>>><>>< B

某 Python スレの書き込みを見ていてふと。

今のところ、これが一番スマート。

    

    
 collection 
    
collection _ 'A <<<><<<>><<<><><<>><<<><<><<<>><<<><<>>>><><<>>< B' asOrderedCollection.
[collection includesAllOf: '<>'] whileTrue: [collection removeAll: '<>'].
^ String withAll: collection

"=> 'A <<<<<<<<<< B' "

大なり小なり部分だけを分離して、後で結合するタイプだと、ソートしていろいろできます。

    

    
 tokens string 
    
tokens _ Scanner new scanTokens: 'A <<<><<<>><<<><><<>><<<><<><<<>><<<><<>>>><><<>>< B'.
string _ tokens second asString sort.
[string includesSubString: '<>'] whileTrue: [
  string _ string copyReplaceAll: '<>' with: ''].
tokens at: 2 put: string.
^ String streamContents: [: s | tokens do: [: e | s nextPutAll: e] separatedBy: [s space]]

    

    
 tokens collection 
    
tokens _ Scanner new scanTokens: 'A <<<><<<>><<<><><<>><<<><<><<<>><<<><<>>>><><<>>< B'.
collection _ tokens second asSortedCollection.
[collection first == collection last] whileFalse: [collection removeFirst; removeLast].
tokens at: 2 put: (String withAll: collection).
^ String streamContents: [: s | tokens do: [: e | s nextPutAll: e] separatedBy: [s space]]

    

    
 array tokens token2 
    
tokens _ Scanner new scanTokens: 'A <<<><<<>><<<><><<>><<<><<><<<>><<<><<>>>><><<>>< B'.
array _ tokens second asSortedArray.
token2 _ String streamContents: [: s | 
  array with: array reverse do: [: a : b | a = b ifTrue: [s nextPut: a]]].
tokens at: 2 put: token2.
^ String streamContents: [: s | tokens do: [: e | s nextPutAll: e] separatedBy: [s space]]

もちろん、ループで回して、じかに数えて差を取るのもありでしょう。面倒ですが…。数えるにしても、a Bag くらいは使いたいですね。ｗ

    

    
 tokens counts first second 
    
tokens _ Scanner new scanTokens: 'A <<<><<<>><<<><><<>><<<><<><<<>><<<><<>>>><><<>>< B'.
counts _ tokens second asBag sortedCounts.
first _ counts first.
second _ counts second.
tokens at: 2 put: (String streamContents: [: s | 
  first key - second key timesRepeat: [s nextPut: first value]]).
^ String streamContents: [: s | tokens do: [: e | s nextPutAll: e] separatedBy: [s space]]