Advent of Code 2016 Day23: Safe Cracking

This is a series of programming challenges for beginners and experienced Caché programmers.

For an introduction : go to article https://community.intersystems.com/post/advent-code-2016-day1-no-time-t…
 

Remember the assembunny language we had to code on day 12 (https://community.intersystems.com/post/advent-code-2016-day12-leonardo…)?

There is a new instruction we have to implement which toggles an instruction x lines away (further or back).

• For one-argument instructions, inc becomes dec, and all other one-argument instructions become inc.
• For two-argument instructions, jnz becomes cpy, and all other two-instructions become jnz.
• The arguments of a toggled instruction are not affected.
• If an attempt is made to toggle an instruction outside the program, nothing happens.
• If toggling produces an invalid instruction (like cpy 1 2) and an attempt is later made to execute that instruction, skip it instead.
• If tgl toggles itself (for example, if a is 0, tgl a would target itself and become inc a), the resulting instruction is not executed until the next time it is reached

Look for http://adventofcode.com/2016/day/23 for the complete explanation.

So we can re-use much of the code we wrote on day 12.

Basically, I included the new instruction, and made the other instructions more robust (since now, we can have 'illegal' values which we need to ignore).

Here is the code i wrote (it is also worth looking in  https://community.intersystems.com/post/advent-code-2016-day12-leonardo…) for the comment that Dmitry wrote about his transpiler of assembunny).

Class AOC2016.Day23 Extends AOC2016.Utils{ClassMethod Part(file As %String = "day23.txt", part As %Integer = 1){  #Dim iInput, counter, next as %Integer  #Dim input, instruction, instruction2, param1, param2 as %String  #Dim var, register, line as %String  For var="a","b","c","d" Set register(var) = 0  set register("a") = $Select(part = 1:7,1:12)

  Try {    Do ..Input(file, .input)    Set iInput = 1    set counter=0    While iInput '> input {      set counter=counter+1      Set line = input(iInput)      Set instruction=$Piece(line," ",1)      Set param1=$Piece(line," ",2)      Set param2=$Piece(line," ",3)      If instruction = "cpy" {        If $Data(register(param2)) Set register(param2)=$Select($Data(register(param1)):register(param1),1:param1)      } elseIf instruction = "inc" {        If $Data(register(param1)) Set register(param1) = register(param1) + 1      } elseIf instruction = "dec" {        If $Data(register(param1)) Set register(param1) = register(param1) - 1      } elseIf instruction = "jnz" {        If $Select($Data(register(param1)):register(param1),1:param1)'=0 {          Set iInput = iInput + $S($Data(register(param2)):register(param2),1:param2) -1 //-1 since every loop will do +1 anyway        }      } elseif instruction = "tgl" {        set next=$Select($Data(register(param1)):register(param1),1:param1)+iInput        If $Data(input(next)) {          set instruction2=$Piece(input(next)," ",1)          If instruction2 = "inc" {            set instruction2="dec"          } elseIf (instruction2="dec")!(instruction2="tgl") {            set instruction2="inc"          } elseIf (instruction2="jnz") {            set instruction2="cpy"          } elseIf (instruction2="cpy") {            set instruction2="jnz"          }          set $Piece(input(next)," ",1)=instruction2        }      }       Set iInput = iInput + 1
      //For part 2 : so we can see why it is so much slower      If (counter#1000000)=0 {        zwrite register        Write "#",iInput,!      }    }
  } catch {
    Write "Error : ",$ZError,!
  }
  Write "register a = ",register("a"),!}}

As you can see, I also included the code for part2, which needs another input for register a.

This causes a change in the flow of instructions which makes the whole process much slower. I show the contents of the registers to let you see what is going on.

Look here for all our solutions so far : https://bitbucket.org/bertsarens/advent2016 and https://github.com/DannyWijnschenk/AdventOfCode2016

Here is the list of all Advent of Code 2016 articles  :

1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25