Day 7 solution

I will probably end up regretting this since I assume the "wait to be given an input from some other process before continuing execution" paradigm is going to come up again, but this part 2 goroutine+channel solution felt good (taking advantage of Go features) and made me happy, so I rolled with it.

days/07.go

@@ -0,0 +1,116 @@
+package days
+
+import (
+	"fmt"
+	"sync"
+
+	"parnic.com/aoc2019/utilities"
+)
+
+type Day07 struct {
+	program utilities.IntcodeProgram
+	amps    []utilities.IntcodeProgram
+}
+
+func (d *Day07) Parse() {
+	d.program = utilities.LoadIntcodeProgram("07p")
+	d.amps = make([]utilities.IntcodeProgram, 5)
+	for i := range d.amps {
+		d.amps[i] = d.program.Copy()
+	}
+}
+
+func (d Day07) Num() int {
+	return 7
+}
+
+func (d *Day07) Part1() string {
+	var highestVal int64
+	var highestSequence []int64
+
+	allSequences := utilities.GetPermutations([]int64{0, 1, 2, 3, 4})
+	for _, sequence := range allSequences {
+		if len(sequence) != len(d.amps) {
+			panic("input sequence does not match up to number of amplifiers")
+		}
+
+		input := int64(0)
+		var output int64
+		for i, amp := range d.amps {
+			amp.RunIn(func(step int) int64 {
+				if step == 1 {
+					return sequence[i]
+				} else if step == 2 {
+					return input
+				}
+
+				panic("hit more input instructions than expected")
+			}, func(val int64, state utilities.IntcodeProgramState) {
+				output = val
+			})
+
+			input = output
+		}
+
+		if output > highestVal {
+			highestVal = output
+			if highestSequence == nil {
+				highestSequence = make([]int64, len(sequence))
+			}
+			copy(highestSequence, sequence)
+		}
+	}
+
+	return fmt.Sprintf("Max thruster signal: %s%d%s (produced by %v)", utilities.TextBold, highestVal, utilities.TextReset, highestSequence)
+}
+
+func (d *Day07) Part2() string {
+	var highestVal int64
+	var highestSequence []int64
+
+	allSequences := utilities.GetPermutations([]int64{5, 6, 7, 8, 9})
+	for _, sequence := range allSequences {
+		if len(sequence) != len(d.amps) {
+			panic("input sequence does not match up to number of amplifiers")
+		}
+
+		inputs := make([]chan int64, len(d.amps))
+		for i := range d.amps {
+			d.amps[i].Reset()
+			inputs[i] = make(chan int64, 1)
+			inputs[i] <- sequence[i]
+		}
+
+		var finalOutput int64
+		var wg sync.WaitGroup
+		for i := range d.amps {
+			wg.Add(1)
+			go func(idx int) {
+				d.amps[idx].RunIn(func(step int) int64 {
+					input := <-inputs[idx]
+					return input
+				}, func(val int64, state utilities.IntcodeProgramState) {
+					finalOutput = val
+					inputIdx := idx + 1
+					if inputIdx == len(inputs) {
+						inputIdx = 0
+					}
+					inputs[inputIdx] <- val
+				})
+				wg.Done()
+			}(i)
+		}
+		inputs[0] <- 0
+		wg.Wait()
+
+		if finalOutput > highestVal {
+			highestVal = finalOutput
+			if highestSequence == nil {
+				highestSequence = make([]int64, len(sequence))
+			}
+			copy(highestSequence, sequence)
+		}
+	}
+
+	return fmt.Sprintf("Max thruster signal: %s%d%s (produced by %v)", utilities.TextBold, highestVal, utilities.TextReset, highestSequence)
+}

inputs/07p.txt

@@ -0,0 +1 @@
+3,8,1001,8,10,8,105,1,0,0,21,38,47,64,85,106,187,268,349,430,99999,3,9,1002,9,4,9,1001,9,4,9,1002,9,4,9,4,9,99,3,9,1002,9,4,9,4,9,99,3,9,1001,9,3,9,102,5,9,9,1001,9,5,9,4,9,99,3,9,101,3,9,9,102,5,9,9,1001,9,4,9,102,4,9,9,4,9,99,3,9,1002,9,3,9,101,2,9,9,102,4,9,9,101,2,9,9,4,9,99,3,9,1002,9,2,9,4,9,3,9,102,2,9,9,4,9,3,9,1001,9,2,9,4,9,3,9,1001,9,1,9,4,9,3,9,101,1,9,9,4,9,3,9,102,2,9,9,4,9,3,9,101,2,9,9,4,9,3,9,102,2,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,1002,9,2,9,4,9,99,3,9,102,2,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,1001,9,1,9,4,9,3,9,1002,9,2,9,4,9,3,9,101,1,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,1001,9,2,9,4,9,3,9,1001,9,1,9,4,9,3,9,101,2,9,9,4,9,3,9,101,1,9,9,4,9,99,3,9,102,2,9,9,4,9,3,9,102,2,9,9,4,9,3,9,1001,9,1,9,4,9,3,9,1002,9,2,9,4,9,3,9,102,2,9,9,4,9,3,9,1002,9,2,9,4,9,3,9,101,1,9,9,4,9,3,9,101,1,9,9,4,9,3,9,101,1,9,9,4,9,3,9,1002,9,2,9,4,9,99,3,9,1002,9,2,9,4,9,3,9,102,2,9,9,4,9,3,9,101,1,9,9,4,9,3,9,1001,9,1,9,4,9,3,9,1002,9,2,9,4,9,3,9,102,2,9,9,4,9,3,9,102,2,9,9,4,9,3,9,101,2,9,9,4,9,3,9,102,2,9,9,4,9,3,9,1002,9,2,9,4,9,99,3,9,1002,9,2,9,4,9,3,9,101,1,9,9,4,9,3,9,102,2,9,9,4,9,3,9,1001,9,2,9,4,9,3,9,1002,9,2,9,4,9,3,9,1002,9,2,9,4,9,3,9,1001,9,1,9,4,9,3,9,1002,9,2,9,4,9,3,9,1001,9,1,9,4,9,3,9,102,2,9,9,4,9,99

inputs/07s1.txt

@@ -0,0 +1 @@
+3,15,3,16,1002,16,10,16,1,16,15,15,4,15,99,0,0

inputs/07s2.txt

@@ -0,0 +1 @@
+3,23,3,24,1002,24,10,24,1002,23,-1,23,101,5,23,23,1,24,23,23,4,23,99,0,0

inputs/07s3.txt

@@ -0,0 +1 @@
+3,31,3,32,1002,32,10,32,1001,31,-2,31,1007,31,0,33,1002,33,7,33,1,33,31,31,1,32,31,31,4,31,99,0,0,0

inputs/07s4.txt

@@ -0,0 +1 @@
+3,26,1001,26,-4,26,3,27,1002,27,2,27,1,27,26,27,4,27,1001,28,-1,28,1005,28,6,99,0,0,5

inputs/07s5.txt

@@ -0,0 +1 @@
+3,52,1001,52,-5,52,3,53,1,52,56,54,1007,54,5,55,1005,55,26,1001,54,-5,54,1105,1,12,1,53,54,53,1008,54,0,55,1001,55,1,55,2,53,55,53,4,53,1001,56,-1,56,1005,56,6,99,0,0,0,0,10

main.go

@@ -37,6 +37,7 @@ var dayMap = []day{
 	&days.Day04{},
 	&days.Day05{},
 	&days.Day06{},
+	&days.Day07{},
 }
 
 func main() {

utilities/permutations.go

@@ -0,0 +1,34 @@
+package utilities
+
+type Permutable interface {
+	~int | ~int8 | ~int16 | ~int32 | ~int64 | ~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64
+}
+
+func GetPermutations[T Permutable](arr []T) [][]T {
+	var helper func([]T, int)
+	res := [][]T{}
+
+	helper = func(arr []T, n int) {
+		if n == 1 {
+			tmp := make([]T, len(arr))
+			copy(tmp, arr)
+			res = append(res, tmp)
+		} else {
+			for i := 0; i < n; i++ {
+				helper(arr, n-1)
+				if n%2 == 1 {
+					tmp := arr[i]
+					arr[i] = arr[n-1]
+					arr[n-1] = tmp
+				} else {
+					tmp := arr[0]
+					arr[0] = arr[n-1]
+					arr[n-1] = tmp
+				}
+			}
+		}
+	}
+
+	helper(arr, len(arr))
+	return res
+}