might be making a mistake starting 2018...

2019/day09/part2/main.go

@@ -0,0 +1,210 @@
+/*
+Intcode struct is defined within this file
+MakePermutations is in the util package as that will likely be reused
+*/
+
+package main
+
+import (
+	"adventofcode/util"
+	"fmt"
+	"log"
+	"strconv"
+	"strings"
+)
+
+func main() {
+	// read the input file, modify it to a slice of numbers
+	inputFile := util.ReadFile("../input.txt")
+
+	splitStrings := strings.Split(inputFile, ",")
+
+	inputNumbers := make([]int, len(splitStrings))
+	for i, v := range splitStrings {
+		inputNumbers[i], _ = strconv.Atoi(v)
+	}
+
+	// initialize a computer with a senor boost input of `2`
+	comp := MakeComputer(inputNumbers, 2)
+	fmt.Println("BOOST keycode is", comp.LastOutput)
+}
+
+/*
+Intcode is an OOP approach *************************************************
+MakeComputer is equivalent to the constructor
+Step takes in an input int and updates properties in the computer:
+	- InstructionIndex: where to read the next instruction from
+	- LastOutput, what the last opcode 4 outputted
+	- PuzzleIndex based if the last instruction modified the puzzle at all
+****************************************************************************/
+type Intcode struct {
+	PhaseSetting     int   // initial input: ID or number used to "prime"/setup the comp
+	PuzzleInput      []int // file/puzzle input parsed into slice of ints
+	InstructionIndex int   // stores the index where the next instruction is
+	RelativeBase     int   // relative base for opcode 9 and param mode 2
+	LastOutput       int   // last output from an opcode 4
+	IsRunning        bool  // will be true until a 99 opcode is hit
+}
+
+// MakeComputer initializes a new comp
+func MakeComputer(PuzzleInput []int, PhaseSetting int) Intcode {
+	puzzleInputCopy := make([]int, len(PuzzleInput))
+	copy(puzzleInputCopy, PuzzleInput)
+
+	comp := Intcode{
+		PhaseSetting,
+		puzzleInputCopy,
+		0,
+		0,
+		0,
+		true,
+	}
+
+	// Prime the computer by running its initial phase setting through it
+	// This will update the comp's InstructionIndex so it's pointing to the next command
+	// will also update the PuzzleInput itself via opcode 3's insert
+	// AND will run the computer until it asks for the next input, _comp is now primed_
+	comp.Step(PhaseSetting)
+	return comp
+}
+
+// Step will read the next 4 values in the input `sli` and make updates
+// according to the opcodes
+func (comp *Intcode) Step(input int) {
+	// read the instruction, opcode and the indexes where the params point to
+	opcode, paramIndexes := comp.GetOpCodeAndParamIndexes()
+	param1, param2, param3 := paramIndexes[0], paramIndexes[1], paramIndexes[2]
+
+	// ensure params are within the bounds of PuzzleInput, resize if necessary
+	comp.ResizeMemory(param1, param2, param3)
+
+	switch opcode {
+	case 99: // 99: Terminates program
+		// fmt.Println("Terminating...")
+		comp.IsRunning = false
+	case 1: // 1: Add next two paramIndexes, store in third
+		comp.PuzzleInput[param3] = comp.PuzzleInput[param1] + comp.PuzzleInput[param2]
+		comp.InstructionIndex += 4
+		comp.Step(input)
+	case 2: // 2: Multiply next two and store in third
+		comp.PuzzleInput[param3] = comp.PuzzleInput[param1] * comp.PuzzleInput[param2]
+		comp.InstructionIndex += 4
+		comp.Step(input)
+	case 3: // 3: Takes one input and saves it to position of one parameter
+		// check if input has already been used (i.e. input == -1)
+		// if it's been used, return out to prevent further Steps
+		// NOTE: making a big assumption that -1 will never be an input...
+		if input == -1 {
+			return
+		}
+
+		// else recurse with a -1 to signal the initial input has been processed
+		comp.PuzzleInput[param1] = input
+		comp.InstructionIndex += 2
+		comp.Step(-1)
+	case 4: // 4: outputs its input value
+		// set LastOutput of the computer & log it
+		comp.LastOutput = comp.PuzzleInput[param1]
+		// fmt.Printf("Opcode 4 output: %v\n", comp.LastOutput)
+		comp.InstructionIndex += 2
+
+		// continue running until terminates or asks for another input
+		comp.Step(input)
+	// 5: jump-if-true: if first param != 0, move pointer to second param, else nothing
+	case 5:
+		if comp.PuzzleInput[param1] != 0 {
+			comp.InstructionIndex = comp.PuzzleInput[param2]
+		} else {
+			comp.InstructionIndex += 3
+		}
+		comp.Step(input)
+	// 6: jump-if-false, if first param == 0 then set instruction pointer to 2nd param, else nothing
+	case 6:
+		if comp.PuzzleInput[param1] == 0 {
+			comp.InstructionIndex = comp.PuzzleInput[param2]
+		} else {
+			comp.InstructionIndex += 3
+		}
+		comp.Step(input)
+	// 7: less-than, if param1 < param2 then store 1 in postion of 3rd param, else store 0
+	case 7:
+		if comp.PuzzleInput[param1] < comp.PuzzleInput[param2] {
+			comp.PuzzleInput[param3] = 1
+		} else {
+			comp.PuzzleInput[param3] = 0
+		}
+		comp.InstructionIndex += 4
+		comp.Step(input)
+	// 8: equals, if param1 == param2 then set position of 3rd param to 1, else store 0
+	case 8:
+		if comp.PuzzleInput[param1] == comp.PuzzleInput[param2] {
+			comp.PuzzleInput[param3] = 1
+		} else {
+			comp.PuzzleInput[param3] = 0
+		}
+		comp.InstructionIndex += 4
+		comp.Step(input)
+	// 9: adjust relative base
+	case 9:
+		comp.RelativeBase += comp.PuzzleInput[param1]
+		comp.InstructionIndex += 2
+		comp.Step(input)
+	default:
+		log.Fatalf("Error: unknown opcode %v at index %v", opcode, comp.PuzzleInput[comp.InstructionIndex])
+	}
+}
+
+/*
+GetOpCodeAndParamIndexes will parse the instruction at comp.PuzzleInput[comp.InstructionIndex]
+- opcode will be the left two digits, mod by 100 will get that
+- rest of instructions will be grabbed via mod 10
+	- these also have to be parsed for the
+*/
+func (comp *Intcode) GetOpCodeAndParamIndexes() (int, [3]int) {
+	instruction := comp.PuzzleInput[comp.InstructionIndex]
+
+	// opcode is the lowest two digits, so mod by 100
+	opcode := instruction % 100
+	instruction /= 100
+
+	// assign the indexes that need to be read by reading the parameter modes
+	var paramIndexes [3]int
+	for i := 1; i <= 3 && comp.InstructionIndex+i < len(comp.PuzzleInput); i++ {
+		// grab the mode with a mod, last digit
+		mode := instruction % 10
+		instruction /= 10
+
+		switch mode {
+		case 0: // position mode, index will be the value at the index
+			paramIndexes[i-1] = comp.PuzzleInput[comp.InstructionIndex+i]
+		case 1: // immediate mode, the index itself
+			paramIndexes[i-1] = comp.InstructionIndex + i
+		case 2: // relative mode, like position mode but index is added to relative base
+			paramIndexes[i-1] = comp.PuzzleInput[comp.InstructionIndex+i] + comp.RelativeBase
+		}
+	}
+
+	return opcode, paramIndexes
+}
+
+// ResizeMemory will take any number of integers and resize the computer's memory appropriately
+func (comp *Intcode) ResizeMemory(sizes ...int) {
+	// get largest of input sizes
+	maxArgSize := sizes[0]
+	for _, v := range sizes {
+		if v > maxArgSize {
+			maxArgSize = v
+		}
+	}
+
+	// resize if PuzzleInput's length is shorter
+	if maxArgSize > len(comp.PuzzleInput) {
+		// make empty slice to copy into, of the new, larger size
+		resizedPuzzleInput := make([]int, maxArgSize)
+		// copy old puzzle input values in
+		copy(resizedPuzzleInput, comp.PuzzleInput)
+
+		// overwrite puzzle input
+		comp.PuzzleInput = resizedPuzzleInput
+	}
+}