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beauvill 2019-10-25 11:52:33 +02:00
parent b1b43ca6e6
commit 604ff923ff
1 changed files with 28 additions and 8 deletions
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36
src/main/scala/forcomp/Anagrams.scala
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@ -33,10 +33,10 @@ object Anagrams extends AnagramsInterface {
*
* Note: you must use `groupBy` to implement this method!
*/
def wordOccurrences(w: Word): Occurrences = ???
def wordOccurrences(w: Word): Occurrences = w.toLowerCase.toSeq.groupBy(e => e).view.mapValues(t => t.length).toList.sorted
/** Converts a sentence into its character occurrence list. */
def sentenceOccurrences(s: Sentence): Occurrences = ???
def sentenceOccurrences(s: Sentence): Occurrences = wordOccurrences(s.mkString)
/** The `dictionaryByOccurrences` is a `Map` from different occurrences to a sequence of all
* the words that have that occurrence count.
@ -53,11 +53,13 @@ object Anagrams extends AnagramsInterface {
* List(('a', 1), ('e', 1), ('t', 1)) -> Seq("ate", "eat", "tea")
*
*/
lazy val dictionaryByOccurrences: Map[Occurrences, List[Word]] = ???
lazy val dictionaryByOccurrences: Map[Occurrences, List[Word]] = dictionary.groupBy(wordOccurrences)
/** Returns all the anagrams of a given word. */
def wordAnagrams(word: Word): List[Word] = ???
def wordAnagrams(word: Word): List[Word] = dictionaryByOccurrences(wordOccurrences(word))
// val o : List[Occurrences] = occurrences.map( x => (for(i <- 1 until (x._2+1)) yield (x._1,i)).toList)
// o.foldRight(List[Occurrences](Nil))((x,y) => y ++ (for(i <- x; j <- y) yield (i :: j)))
/** Returns the list of all subsets of the occurrence list.
* This includes the occurrence itself, i.e. `List(('k', 1), ('o', 1))`
* is a subset of `List(('k', 1), ('o', 1))`.
@ -80,7 +82,10 @@ object Anagrams extends AnagramsInterface {
* Note that the order of the occurrence list subsets does not matter -- the subsets
* in the example above could have been displayed in some other order.
*/
def combinations(occurrences: Occurrences): List[Occurrences] = ???
def combinations(occurrences: Occurrences): List[Occurrences] =
occurrences.map( x => (for(i <- 1 until (x._2+1)) yield (x._1,i)).toList)
.foldRight(List[Occurrences](Nil))((x,y) =>
y ::: (for(i <- x; j <- y) yield (i :: j)))
/** Subtracts occurrence list `y` from occurrence list `x`.
*
@ -92,7 +97,10 @@ object Anagrams extends AnagramsInterface {
* Note: the resulting value is an occurrence - meaning it is sorted
* and has no zero-entries.
*/
def subtract(x: Occurrences, y: Occurrences): Occurrences = ???
def subtract(x: Occurrences, y: Occurrences): Occurrences =
y.foldLeft(Map(x: _*))((map, pair) => {
map.updated(pair._1, map.apply(pair._1) - pair._2)
}).filter(e => e._2 !=0 ).toList.sorted
/** Returns a list of all anagram sentences of the given sentence.
*
@ -134,7 +142,19 @@ object Anagrams extends AnagramsInterface {
*
* Note: There is only one anagram of an empty sentence.
*/
def sentenceAnagrams(sentence: Sentence): List[Sentence] = ???
def sentenceAnagrams(sentence: Sentence): List[Sentence] = {
def iter(occurrences: Occurrences): List[Sentence] = {
if (occurrences.isEmpty) List(Nil)
else for {
combination <- combinations( occurrences )
word <- dictionaryByOccurrences getOrElse (combination, Nil)
sentence <- iter( subtract(occurrences,wordOccurrences(word)) )
if !combination.isEmpty
} yield word :: sentence
}
iter( sentenceOccurrences(sentence) )
}
}
object Dictionary {