Initial data commit

Task/Burrows-Wheeler-transform/Scala/burrows-wheeler-transform.scala

@@ -0,0 +1,66 @@
+import scala.collection.mutable.ArrayBuffer
+
+object BWT {
+  val STX = '\u0002'
+  val ETX = '\u0003'
+
+  def bwt(s: String): String = {
+    if (s.contains(STX) || s.contains(ETX)) {
+      throw new RuntimeException("String can't contain STX or ETX")
+    }
+    var ss = STX + s + ETX
+    var table = new ArrayBuffer[String]()
+    (0 until ss.length).foreach(_ => {
+      table += ss
+      ss = ss.substring(1) + ss.charAt(0)
+    })
+    table.sorted.map(a => a.last).mkString
+  }
+
+  def ibwt(r: String): String = {
+    var table = Array.fill(r.length)("")
+    (0 until r.length).foreach(_ => {
+      (0 until r.length).foreach(i => {
+        table(i) = r.charAt(i) + table(i)
+      })
+      table = table.sorted
+    })
+    table.indices.foreach(i => {
+      val row = table(i)
+      if (row.last == ETX) {
+        return row.substring(1, row.length - 1)
+      }
+    })
+    ""
+  }
+
+  def makePrintable(s: String): String = {
+    s.replace(STX, '^').replace(ETX, '|')
+  }
+
+  def main(args: Array[String]): Unit = {
+    val tests = Array("banana",
+      "appellee",
+      "dogwood",
+      "TO BE OR NOT TO BE OR WANT TO BE OR NOT?",
+      "SIX.MIXED.PIXIES.SIFT.SIXTY.PIXIE.DUST.BOXES",
+      "\u0002ABC\u0003"
+    )
+
+    tests.foreach(test => {
+      println(makePrintable(test))
+      print(" --> ")
+
+      try {
+        val t = bwt(test)
+        println(makePrintable(t))
+        val r = ibwt(t)
+        printf(" --> %s\n", r)
+      } catch {
+        case e: Exception => printf("ERROR: %s\n", e.getMessage)
+      }
+
+      println()
+    })
+  }
+}