168 // memory at the current location to 0. In the compute3 and run3 functions

   168 // memory at the current location to 0. In the compute3 and run3 functions

   169 // below you implement this command by writing the number 0 to mem(mp), 

   169 // below you implement this command by writing the number 0 to mem(mp), 

   170 // that is write(mem, mp, 0). 

   170 // that is write(mem, mp, 0). 

   171 //

   171 //

   172 // The easiest way to modify a string in this way is to use the regular

   172 // The easiest way to modify a string in this way is to use the regular

   174 // not a bf-command and replace it by the empty string. Similarly the

   174 // not a bf-command and replace it by the empty string. Similarly the

   175 // regular expression """\[-\]""" finds all occurences of [-] and 

   175 // regular expression """\[-\]""" finds all occurences of [-] and 

   176 // by using the Scala method .replaceAll you can repplace it with the 

   176 // by using the Scala method .replaceAll you can repplace it with the 

   177 // string "0" standing for the new bf-command.

   177 // string "0" standing for the new bf-command.

   178 

   178 

   179 def optimise(s: String) : String = {

   179 def optimise(s: String) : String = {

   181    .replaceAll("""\[-\]""", "0")

   181    .replaceAll("""\[-\]""", "0")

   182 }

   182 }

   183 

   183 

   184 

   184 

   185 def compute3(pg: String, tb: Map[Int, Int], pc: Int, mp: Int, mem: Mem) : Mem = {

   185 def compute3(pg: String, tb: Map[Int, Int], pc: Int, mp: Int, mem: Mem) : Mem = {