たかし君からの問いかけ、その２

shiritori.scala

/**
 * http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=0225
 * 
 * 回文問題
 * 
 * #scala_kansai_beginners
 */

var buff = List(
"apple",
"yellow",
"georgia",
"king",
"email",
"lucky",
"wink", "aaaaa")

/** 一つのながい回文にして、頭と尻を比較して判定 */
var loopword = loop_words(buff)
//println(loopword)
println(if (loopword.length != 0 && loopword.last == loopword.head) "OK" else "NG")


// wordが頭に合うの探して、単語を返す
def findWord (list:List[String], word:Char): String = {
    if (list.length == 0) return ""

    return if (list.head.head == word) list.head
            else findWord(list.tail, word)
}

// 一つ目の要素を長い回文にする
def loop_words (list:List[String]):String = {
    if (list.length == 1) return list.head

    var word = findWord(list.tail, list.head.last)
    var words = list.head + word
    return if (word != "")
            loop_words(List.concat(List(words),list.tail.filter(fn => fn != word)))
        else
            ""
}