--- Day 4: JollyScript Bootcamp ---
You've barely had the chance to rest on your laurels when Patch comes banging on the (gingerbread) door of your (gingerbread) hotel room.
"You did a great job back there, real jolly! Real merry!" He says through gritted teeth.
You're confused -- you wrote a pretty neat algo for the Confectionery Lab's Accelerator, didn't you? There must be something else going on... you throw on your new Santa x Lululemon x Cambridge hoodie and brace for the biting North Pole frost.
You catch Patch muttering to himself; "That was my chance! To bust the elf union! Now santa's gonna be SO mad..."
When he sees you, he flips on the merry switch and leads you excitedly outside.
"Really, that was fantastic! Super impressive! We've been talking and I think it's time for you to tackle one of the most serious bugs this Christmas -- a crucial microservice in the Holiday Algorithm has failed, and isn't outputting what it should."
You take a deep breath. After all that Ocaml training, you can deal with ANY esolang. "It's written in JollyScript, isn't it."
"It's the only programming language optimised for festive efficiency!" Patch exclaims unintelligently.
"You said that yesterday, though?"
"I wish I could say it every day!"
JollyScript is an enterprise-grade language for intelligent elves. It's so festive, that every JollyScript program is shaped like a Christmas tree!
JollyScript operates on a stack of 4-bit integers, also known as nibbles.
The program is executed via a cursor on a 2-dimensional grid. The cursor starts at the asterisk symbol *, usually at the top of the tree, and moves downwards diagonally.
It can go either left or right, but its initial direction is left.
After the cursor encounters a command, it continues in the same direction as before, unless the command changes the direction. Here are the commands for JollyScript:
/: Set the direction to left.\: Set the direction to right.^: Fork the program into two serial (non-parallel) threads, one going left, and one going right. Run the left in the left direction completely. When that terminates, run the right branch.~: Terminate this thread.+: Pop a, then pop b. Push a + b onto the stack.-: Pop a, then pop b. Push b - a onto the stack.:: Duplicate the top of the stack.%: Swap the top two values of the stack.$: Pop and discard the top of the stack.?: Look at the top of the stack. If it is zero, set the direction to left. Otherwise, decrement the top of the stack, and set the direction to right.0-9, A-F: Push a hexadecimal digit onto the stack..: Print the top of the stack as a hexadecimal digit.": Toggle printing mode. Characters encountered will instead be printed until printing mode is turned off.n: Print a newline.{: Remember this cursor location (but not the direction).}: Go back to the location you remembered, continuing in the same direction.The following is an example program in JollyScript.
*
{
^ \
^ \ ^
^ - ? "
4 % . n #
5 . } n "
~~~~~~~~~~~~~
|_|
This is the output of the example program.
41
#00
As you grab your tools and head to the JollyScript Console, the elves cheer behind you. "You're the only one who can fix this! We believe in you!"
You've been tasked with debugging a program that's supposed to print the Twelve Days of Christmas. Due to clumsy elf fingers, exactly one character in the program is wrong!
Can you find the bug?
Your answer should be the location of the incorrect character, in the format (line number, column number).