Brainfuck interpreter

Author: mukel

HackerRank/Misc/Brainfuck.scala

@@ -0,0 +1,39 @@
+object Solution {
+  def execute(program: String, input: Iterator[Char]): Unit = {
+    val mem = Array.ofDim[Int](1 << 16)
+    var dataPtr, instPtr = 0
+    var iterations = 100000
+    val twinBracket = Array.ofDim[Int](program.size)
+    val s = scala.collection.mutable.Stack[Int]()
+	for (i <- program.indices) {
+    	if (program(i) == '[') s.push(i)
+    	if (program(i) == ']') {
+    		twinBracket(i) = s.top
+    		twinBracket(s.pop) = i
+    	}
+    }
+    while (iterations > 0 && instPtr < program.size) {
+      program(instPtr) match {
+        case '+' => mem(dataPtr) = (mem(dataPtr) + 1) % 256
+        case '-' => mem(dataPtr) = (mem(dataPtr) - 1 + 256) % 256
+        case '.' => print(mem(dataPtr).toChar)
+        case ',' => mem(dataPtr) = input.next().toByte
+        case '<' => dataPtr -= 1
+        case '>' => dataPtr += 1
+        case '[' => if (mem(dataPtr) == 0) instPtr = twinBracket(instPtr) - 1
+        case ']' => if (mem(dataPtr) != 0) instPtr = twinBracket(instPtr) - 1        
+      }
+      instPtr += 1
+      iterations -= 1
+    }
+    if (instPtr < program.size)
+      println("\nPROCESS TIME OUT. KILLED!!!")
+  }
+
+  def main(args: Array[String]): Unit = {
+    val programLineCount = (readLine split " ")(1).toInt
+    val input = readLine
+    val program = Seq.fill(programLineCount)(readLine).mkString.filter ("<>+-.,[]" contains _)
+    execute(program, input.toIterator)
+  }
+}