185 lines
8.2 KiB
Org Mode
185 lines
8.2 KiB
Org Mode
** --- Day 5: Sunny with a Chance of Asteroids ---
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You're starting to sweat as the ship makes its way toward Mercury. The
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Elves suggest that you get the air conditioner working by upgrading your
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ship computer to support the Thermal Environment Supervision Terminal.
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The Thermal Environment Supervision Terminal (TEST) starts by running a
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/diagnostic program/ (your puzzle input). The TEST diagnostic program
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will run on [[file:2][your existing Intcode computer]] after a few
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modifications:
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/First/, you'll need to add /two new instructions/:
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- Opcode =3= takes a single integer as /input/ and saves it to the
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position given by its only parameter. For example, the instruction
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=3,50= would take an input value and store it at address =50=.
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- Opcode =4= /outputs/ the value of its only parameter. For example, the
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instruction =4,50= would output the value at address =50=.
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Programs that use these instructions will come with documentation that
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explains what should be connected to the input and output. The program
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=3,0,4,0,99= outputs whatever it gets as input, then halts.
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/Second/, you'll need to add support for /parameter modes/:
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Each parameter of an instruction is handled based on its parameter mode.
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Right now, your ship computer already understands parameter mode =0=,
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/position mode/, which causes the parameter to be interpreted as a
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/position/ - if the parameter is =50=, its value is /the value stored at
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address =50= in memory/. Until now, all parameters have been in position
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mode.
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Now, your ship computer will also need to handle parameters in mode =1=,
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/immediate mode/. In immediate mode, a parameter is interpreted as a
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/value/ - if the parameter is =50=, its value is simply /=50=/.
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Parameter modes are stored in the same value as the instruction's
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opcode. The opcode is a two-digit number based only on the ones and tens
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digit of the value, that is, the opcode is the rightmost two digits of
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the first value in an instruction. Parameter modes are single digits,
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one per parameter, read right-to-left from the opcode: the first
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parameter's mode is in the hundreds digit, the second parameter's mode
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is in the thousands digit, the third parameter's mode is in the
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ten-thousands digit, and so on. Any missing modes are =0=.
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For example, consider the program =1002,4,3,4,33=.
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The first instruction, =1002,4,3,4=, is a /multiply/ instruction - the
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rightmost two digits of the first value, =02=, indicate opcode =2=,
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multiplication. Then, going right to left, the parameter modes are =0=
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(hundreds digit), =1= (thousands digit), and =0= (ten-thousands digit,
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not present and therefore zero):
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#+BEGIN_EXAMPLE
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ABCDE
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1002
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DE - two-digit opcode, 02 == opcode 2
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C - mode of 1st parameter, 0 == position mode
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B - mode of 2nd parameter, 1 == immediate mode
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A - mode of 3rd parameter, 0 == position mode,
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omitted due to being a leading zero
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#+END_EXAMPLE
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This instruction multiplies its first two parameters. The first
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parameter, =4= in position mode, works like it did before - its value is
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the value stored at address =4= (=33=). The second parameter, =3= in
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immediate mode, simply has value =3=. The result of this operation,
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=33 * 3 = 99=, is written according to the third parameter, =4= in
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position mode, which also works like it did before - =99= is written to
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address =4=.
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Parameters that an instruction writes to will /never be in immediate
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mode/.
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/Finally/, some notes:
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- It is important to remember that the instruction pointer should
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increase by /the number of values in the instruction/ after the
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instruction finishes. Because of the new instructions, this amount is
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no longer always =4=.
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- Integers can be negative: =1101,100,-1,4,0= is a valid program (find
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=100 + -1=, store the result in position =4=).
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The TEST diagnostic program will start by requesting from the user the
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ID of the system to test by running an /input/ instruction - provide it
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=1=, the ID for the ship's air conditioner unit.
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It will then perform a series of diagnostic tests confirming that
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various parts of the Intcode computer, like parameter modes, function
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correctly. For each test, it will run an /output/ instruction indicating
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how far the result of the test was from the expected value, where =0=
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means the test was successful. Non-zero outputs mean that a function is
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not working correctly; check the instructions that were run before the
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output instruction to see which one failed.
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Finally, the program will output a /diagnostic code/ and immediately
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halt. This final output isn't an error; an output followed immediately
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by a halt means the program finished. If all outputs were zero except
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the diagnostic code, the diagnostic program ran successfully.
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After providing =1= to the only input instruction and passing all the
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tests, /what diagnostic code does the program produce?/
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Your puzzle answer was =10987514=.
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** --- Part Two ---
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The air conditioner comes online! Its cold air feels good for a while,
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but then the TEST alarms start to go off. Since the air conditioner
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can't vent its heat anywhere but back into the spacecraft, it's actually
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making the air inside the ship /warmer/.
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Instead, you'll need to use the TEST to extend the
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[[https://en.wikipedia.org/wiki/Spacecraft_thermal_control][thermal
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radiators]]. Fortunately, the diagnostic program (your puzzle input) is
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already equipped for this. Unfortunately, your Intcode computer is not.
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Your computer is only missing a few opcodes:
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- Opcode =5= is /jump-if-true/: if the first parameter is /non-zero/, it
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sets the instruction pointer to the value from the second parameter.
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Otherwise, it does nothing.
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- Opcode =6= is /jump-if-false/: if the first parameter /is zero/, it
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sets the instruction pointer to the value from the second parameter.
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Otherwise, it does nothing.
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- Opcode =7= is /less than/: if the first parameter is /less than/ the
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second parameter, it stores =1= in the position given by the third
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parameter. Otherwise, it stores =0=.
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- Opcode =8= is /equals/: if the first parameter is /equal to/ the
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second parameter, it stores =1= in the position given by the third
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parameter. Otherwise, it stores =0=.
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Like all instructions, these instructions need to support /parameter
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modes/ as described above.
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Normally, after an instruction is finished, the instruction pointer
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increases by the number of values in that instruction. /However/, if the
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instruction modifies the instruction pointer, that value is used and the
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instruction pointer is /not automatically increased/.
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For example, here are several programs that take one input, compare it
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to the value =8=, and then produce one output:
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- =3,9,8,9,10,9,4,9,99,-1,8= - Using /position mode/, consider whether
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the input is /equal to/ =8=; output =1= (if it is) or =0= (if it is
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not).
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- =3,9,7,9,10,9,4,9,99,-1,8= - Using /position mode/, consider whether
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the input is /less than/ =8=; output =1= (if it is) or =0= (if it is
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not).
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- =3,3,1108,-1,8,3,4,3,99= - Using /immediate mode/, consider whether
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the input is /equal to/ =8=; output =1= (if it is) or =0= (if it is
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not).
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- =3,3,1107,-1,8,3,4,3,99= - Using /immediate mode/, consider whether
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the input is /less than/ =8=; output =1= (if it is) or =0= (if it is
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not).
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Here are some jump tests that take an input, then output =0= if the
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input was zero or =1= if the input was non-zero:
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- =3,12,6,12,15,1,13,14,13,4,13,99,-1,0,1,9= (using /position mode/)
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- =3,3,1105,-1,9,1101,0,0,12,4,12,99,1= (using /immediate mode/)
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Here's a larger example:
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#+BEGIN_EXAMPLE
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3,21,1008,21,8,20,1005,20,22,107,8,21,20,1006,20,31,
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1106,0,36,98,0,0,1002,21,125,20,4,20,1105,1,46,104,
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999,1105,1,46,1101,1000,1,20,4,20,1105,1,46,98,99
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#+END_EXAMPLE
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The above example program uses an input instruction to ask for a single
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number. The program will then output =999= if the input value is below
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=8=, output =1000= if the input value is equal to =8=, or output =1001=
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if the input value is greater than =8=.
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This time, when the TEST diagnostic program runs its input instruction
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to get the ID of the system to test, /provide it =5=/, the ID for the
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ship's thermal radiator controller. This diagnostic test suite only
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outputs one number, the /diagnostic code/.
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/What is the diagnostic code for system ID =5=?/
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Your puzzle answer was =14195011=.
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Both parts of this puzzle are complete! They provide two gold stars: **
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