Day 15 Part 2

Well...that turned out easier than I thought. I suspected this solution would work, but wasn't completely confident. It can only work for the type of maze used by this problem (where there are no loops of open areas).

days/07.go

@@ -28,7 +28,7 @@ func (d *Day07) Part1() string {
 	var highestVal int64
 	var highestSequence []int64
 
-	allSequences := utilities.GetPermutations([]int64{0, 1, 2, 3, 4})
+	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")
@@ -68,7 +68,7 @@ func (d *Day07) Part2() string {
 	var highestVal int64
 	var highestSequence []int64
 
-	allSequences := utilities.GetPermutations([]int64{5, 6, 7, 8, 9})
+	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")

days/14.go

@@ -10,18 +10,15 @@ import (
 )
 
 type reaction struct {
-	inputs map[string]int
+	inputs map[string]int64
 	output u.Pair[string, int]
 }
 
 type Day14 struct {
 	reactions []reaction
-	leftovers map[string]int
 }
 
 func (d *Day14) Parse() {
-	d.leftovers = make(map[string]int)
-
 	lines := u.GetStringLines("14p")
 	d.reactions = make([]reaction, len(lines))
 	for i, line := range lines {
@@ -32,10 +29,10 @@ func (d *Day14) Parse() {
 		outPair := strings.Split(output, " ")
 		outAmt, _ := strconv.Atoi(outPair[0])
 		d.reactions[i].output = u.Pair[string, int]{First: outPair[1], Second: outAmt}
-		d.reactions[i].inputs = make(map[string]int)
+		d.reactions[i].inputs = make(map[string]int64)
 		for _, input := range inputs {
 			pair := strings.Split(input, " ")
-			d.reactions[i].inputs[pair[1]], _ = strconv.Atoi(pair[0])
+			d.reactions[i].inputs[pair[1]], _ = strconv.ParseInt(pair[0], 10, 64)
 		}
 	}
 }
@@ -54,7 +51,7 @@ func (d Day14) Num() int {
 	return 14
 }
 
-func (d *Day14) oreRequiredStock(qty int64) int64 {
+func (d *Day14) getOreRequiredForFuel(qty int64) int64 {
 	oreRequired := int64(0)
 	needs := map[string]int64{
 		"FUEL": qty,
@@ -62,33 +59,36 @@ func (d *Day14) oreRequiredStock(qty int64) int64 {
 	excess := make(map[string]int64)
 
 	getFromExcess := func(qty int64, chemical string) int64 {
-		inStock := excess[chemical]
-		qty -= inStock
-		excess[chemical] = int64(math.Min(math.Abs(float64(qty)), 0))
-		return inStock - excess[chemical]
+		available := u.Min(excess[chemical], qty)
+		excess[chemical] -= available
+		return available
 	}
 
 	for len(needs) > 0 {
 		keys := u.MapKeys(needs)
-		chemical := keys[len(keys)-1]
-		qtyRequired := needs[chemical]
-		delete(needs, chemical)
+		producing := keys[0]
+		qtyRequired := needs[producing]
+		delete(needs, producing)
 
-		fromExcess := getFromExcess(qtyRequired, chemical)
+		fromExcess := getFromExcess(qtyRequired, producing)
+		if fromExcess == qtyRequired {
+			continue
+		}
 		qtyRequired -= fromExcess
 
-		reaction := d.getReactionProducing(chemical)
+		reaction := d.getReactionProducing(producing)
+
 		qtyProduced := int64(reaction.output.Second)
-		ingredients := reaction.inputs
+		reactionsNeeded := int64(math.Ceil(float64(qtyRequired) / float64(qtyProduced)))
 
-		n := int64(math.Ceil(float64(qtyRequired) / float64(qtyProduced)))
+		excess[producing] = (qtyProduced * reactionsNeeded) - qtyRequired
 
-		excess[chemical] = (qtyProduced * n) - qtyRequired
-		for ingredient, qtyIngredient := range ingredients {
-			if ingredient == "ORE" {
-				oreRequired += int64(int64(qtyIngredient) * n)
+		for reagent, inputQty := range reaction.inputs {
+			qtyNeeded := inputQty * reactionsNeeded
+			if reagent == "ORE" {
+				oreRequired += qtyNeeded
 			} else {
-				needs[ingredient] += int64(qtyIngredient) * n
+				needs[reagent] += qtyNeeded
 			}
 		}
 	}
@@ -97,13 +97,13 @@ func (d *Day14) oreRequiredStock(qty int64) int64 {
 }
 
 func (d *Day14) Part1() string {
-	neededOre := d.oreRequiredStock(1)
+	neededOre := d.getOreRequiredForFuel(1)
 	return fmt.Sprintf("%s%d%s", u.TextBold, neededOre, u.TextReset)
 }
 
 func (d *Day14) Part2() string {
 	oreAvailable := int64(1000000000000)
-	estimate := oreAvailable / d.oreRequiredStock(1)
+	estimate := oreAvailable / d.getOreRequiredForFuel(1)
 
 	high := estimate * 2
 	low := estimate
@@ -112,15 +112,17 @@ func (d *Day14) Part2() string {
 	lastFailure := high
 	fuelProduced := low
 
-	for math.Abs(float64(lastFailure)-float64(lastSuccess)) > 1 {
-		oreConsumed := d.oreRequiredStock(fuelProduced)
+	for math.Abs(float64(lastFailure-lastSuccess)) > 1 {
+		oreConsumed := d.getOreRequiredForFuel(fuelProduced)
+		adjustment := (lastFailure - lastSuccess) / 2
 		if oreConsumed < oreAvailable {
 			lastSuccess = fuelProduced
-			fuelProduced += (lastFailure - lastSuccess) / 2
 		} else {
 			lastFailure = fuelProduced
-			fuelProduced -= (lastFailure - lastSuccess) / 2
+			adjustment = -adjustment
 		}
+
+		fuelProduced += adjustment
 	}
 
 	return fmt.Sprintf("%s%d%s", u.TextBold, lastSuccess, u.TextReset)

days/15.go

@@ -0,0 +1,332 @@
+package days
+
+//go:generate stringer -type=cellStatus,responseType,dirType -output=15_types_string.go
+
+import (
+	"fmt"
+	"math"
+	"sort"
+
+	u "parnic.com/aoc2019/utilities"
+)
+
+type point u.Pair[int, int]
+type cellStatus int
+type responseType int
+type dirType int
+
+const (
+	cellStatusUnknown cellStatus = iota
+	cellStatusWall
+	cellStatusOpen
+	cellStatusGoal
+)
+
+const (
+	responseWall responseType = iota
+	responseSuccess
+	responseFoundGoal
+)
+
+const maxVisited = 3
+
+const (
+	dirNorth dirType = iota + 1
+	dirSouth
+	dirWest
+	dirEast
+
+	dirFirst = dirNorth
+	dirLast  = dirEast
+)
+
+var dirOrders = [][]dirType{
+	{dirNorth, dirSouth, dirWest, dirEast},
+	{dirSouth, dirWest, dirEast, dirNorth},
+	{dirWest, dirEast, dirNorth, dirSouth},
+	{dirEast, dirNorth, dirSouth, dirWest},
+}
+
+// turned out to be unnecessary on multiple datasets i tried. increases the iterations 6x
+// var dirOrders = u.GetPermutations(dirNorth, dirSouth, dirWest, dirEast)
+
+type visitedStatus struct {
+	timesVisited      int
+	distanceFromStart int
+}
+
+type Day15 struct {
+	program      u.IntcodeProgram
+	grid         map[point]cellStatus
+	visited      map[point]*visitedStatus
+	shortestPath []point
+	pos          point
+	goalPos      point
+}
+
+func (d *Day15) Parse() {
+	d.program = u.LoadIntcodeProgram("15p")
+	d.grid = map[point]cellStatus{
+		{First: 0, Second: 0}: cellStatusOpen,
+	}
+	d.visited = map[point]*visitedStatus{
+		{First: 0, Second: 0}: {timesVisited: 1},
+	}
+	d.shortestPath = []point{{}}
+}
+
+func (d Day15) Num() int {
+	return 15
+}
+
+func (d Day15) getPointInDirection(pos point, dir dirType) point {
+	target := pos
+	switch dir {
+	case dirNorth:
+		target.First--
+	case dirSouth:
+		target.First++
+	case dirWest:
+		target.Second--
+	case dirEast:
+		target.Second++
+	}
+
+	return target
+}
+
+func (d Day15) getCellTypeInDirection(pos point, dir dirType) (cellStatus, point) {
+	target := d.getPointInDirection(pos, dir)
+	return d.grid[target], target
+}
+
+func (d Day15) getAdjacentCellsOfType(pos point, cellType cellStatus) []point {
+	points := make([]point, 0, 4)
+	for i := dirFirst; i <= dirLast; i++ {
+		adjacentCell := d.getPointInDirection(pos, i)
+		if d.grid[adjacentCell] == cellType {
+			points = append(points, adjacentCell)
+		}
+	}
+	return points
+}
+
+func (d Day15) getDirToNextCellType(pos point, t cellStatus, maxNumVisited int, dirs []dirType) (dirType, point, error) {
+	for _, dir := range dirs {
+		cellInDirection, targetCell := d.getCellTypeInDirection(pos, dir)
+		if cellInDirection == t {
+			_, visitedTargetExists := d.visited[targetCell]
+			foundUnknown := t == cellStatusUnknown && !visitedTargetExists
+			foundOther := t != cellStatusUnknown && visitedTargetExists && d.visited[targetCell].timesVisited <= maxNumVisited
+			if foundUnknown || foundOther {
+				return dir, targetCell, nil
+			}
+		}
+	}
+
+	return dirFirst, point{}, fmt.Errorf("no %v tiles around %v", t, pos)
+}
+
+func (d *Day15) Draw() {
+	min := point{First: math.MaxInt, Second: math.MaxInt}
+	max := point{First: math.MinInt, Second: math.MinInt}
+	for p := range d.grid {
+		if p.First < min.First {
+			min.First = p.First
+		}
+		if p.First > max.First {
+			max.First = p.First
+		}
+		if p.Second < min.Second {
+			min.Second = p.Second
+		}
+		if p.Second > max.Second {
+			max.Second = p.Second
+		}
+	}
+
+	for x := min.First; x <= max.First; x++ {
+		for y := min.Second; y <= max.Second; y++ {
+			p := point{First: x, Second: y}
+			switch d.grid[p] {
+			case cellStatusGoal:
+				fmt.Printf("%s@%s", u.ColorBrightGreen, u.TextReset)
+			case cellStatusOpen:
+				if p == d.pos {
+					fmt.Print(u.BackgroundBrightRed)
+				} else if x == 0 && y == 0 {
+					fmt.Print(u.BackgroundYellow)
+				} else if u.ArrayContains(d.shortestPath, p) {
+					fmt.Print(u.BackgroundGreen)
+				} else if d.visited[p] != nil && d.visited[p].timesVisited > maxVisited {
+					fmt.Print(u.ColorYellow)
+					fmt.Print(u.BackgroundBlack)
+				} else if d.visited[p] != nil && d.visited[p].timesVisited > 1 {
+					fmt.Print(u.BackgroundMagenta)
+				} else {
+					fmt.Print(u.BackgroundBlue)
+				}
+				fmt.Printf(".%s", u.TextReset)
+			case cellStatusWall:
+				fmt.Print("█")
+			case cellStatusUnknown:
+				fmt.Print(" ")
+			}
+		}
+		fmt.Println()
+	}
+}
+
+func (d *Day15) markShortestPath() {
+	pos := d.goalPos
+	checkOffsets := []point{
+		{First: -1, Second: 0},
+		{First: 1, Second: 0},
+		{First: 0, Second: -1},
+		{First: 0, Second: 1},
+	}
+
+	checkPt := func(pt point) (bool, int) {
+		if v, exists := d.visited[pt]; exists && d.grid[pt] == cellStatusOpen {
+			return true, v.distanceFromStart
+		}
+		return false, math.MaxInt
+	}
+
+	d.shortestPath = []point{d.goalPos}
+
+	for pos.First != 0 || pos.Second != 0 {
+		lowestDist := math.MaxInt
+		lowestPoint := point{}
+		for _, pt := range checkOffsets {
+			newPt := point{First: pos.First + pt.First, Second: pos.Second + pt.Second}
+			if found, dist := checkPt(newPt); found && dist < lowestDist {
+				lowestDist = dist
+				lowestPoint = newPt
+			}
+		}
+
+		d.shortestPath = append(d.shortestPath, lowestPoint)
+		pos = lowestPoint
+	}
+}
+
+func (d *Day15) exploreFullMap() map[point]*visitedStatus {
+	grids := make([]map[point]cellStatus, 0, len(dirOrders))
+	goalVisited := d.visited
+
+	for _, dirOrder := range dirOrders {
+		d.program.Reset()
+
+		targetPos := point{}
+		nextDir := dirFirst
+		distFromStart := 0
+
+		d.pos = point{}
+		d.visited = map[point]*visitedStatus{
+			{First: 0, Second: 0}: {timesVisited: 1},
+		}
+		d.grid = map[point]cellStatus{
+			{First: 0, Second: 0}: cellStatusOpen,
+		}
+		d.program.RunIn(func(inputStep int) int64 {
+			var err error
+			nextDir, targetPos, err = d.getDirToNextCellType(d.pos, cellStatusUnknown, 0, dirOrder)
+			if err != nil {
+				// ensure we never try to go back into the trapped spot
+				d.visited[d.pos].timesVisited = maxVisited + 1
+				for x := 1; x <= maxVisited && err != nil; x++ {
+					nextDir, targetPos, err = d.getDirToNextCellType(d.pos, cellStatusOpen, x, dirOrder)
+				}
+			}
+			if err != nil {
+				// d.Draw()
+				// panic(err)
+				d.program.Stop()
+			}
+
+			return int64(nextDir)
+		}, func(val int64, state u.IntcodeProgramState) {
+			rVal := responseType(val)
+
+			p := d.getPointInDirection(d.pos, nextDir)
+			shouldMove := true
+			switch rVal {
+			case responseWall:
+				d.grid[p] = cellStatusWall
+				shouldMove = false
+			case responseSuccess:
+				d.grid[p] = cellStatusOpen
+			case responseFoundGoal:
+				d.grid[p] = cellStatusGoal
+			}
+
+			if shouldMove {
+				d.pos = targetPos
+				if d.visited[d.pos] == nil {
+					d.visited[d.pos] = &visitedStatus{}
+					distFromStart++
+				} else {
+					distFromStart--
+				}
+				d.visited[d.pos].timesVisited++
+				d.visited[d.pos].distanceFromStart = distFromStart
+			}
+
+			if rVal == responseFoundGoal {
+				// d.Draw()
+				d.goalPos = targetPos
+				goalVisited = d.visited
+			}
+		})
+
+		grids = append(grids, d.grid)
+	}
+
+	d.grid = map[point]cellStatus{
+		{First: 0, Second: 0}: cellStatusOpen,
+	}
+	for _, grid := range grids {
+		keys := u.MapKeys(grid)
+		for _, key := range keys {
+			d.grid[key] = grid[key]
+		}
+	}
+
+	return goalVisited
+}
+
+func (d *Day15) tagDistanceRecursive(pos, last point, dist int, distances map[point]int) {
+	distances[pos] = dist
+	for _, cell := range d.getAdjacentCellsOfType(pos, cellStatusOpen) {
+		if cell == last {
+			continue
+		}
+		d.tagDistanceRecursive(cell, pos, dist+1, distances)
+	}
+}
+
+func (d *Day15) Part1() string {
+	d.visited = d.exploreFullMap()
+	d.markShortestPath()
+
+	for _, visited := range d.visited {
+		visited.timesVisited = 1
+	}
+	d.pos = point{}
+	d.Draw()
+
+	return fmt.Sprintf("Moves required to reach target: %s%d%s", u.TextBold, d.visited[d.goalPos].distanceFromStart, u.TextReset)
+}
+
+func (d *Day15) Part2() string {
+	startLoc := d.goalPos
+	distanceMap := map[point]int{startLoc: 0}
+
+	d.tagDistanceRecursive(startLoc, point{}, 0, distanceMap)
+
+	cellDistances := u.MapValues(distanceMap)
+	sort.Slice(cellDistances, func(i, j int) bool { return cellDistances[i] > cellDistances[j] })
+
+	return fmt.Sprintf("%s%d%s", u.TextBold, cellDistances[0], u.TextReset)
+}

days/15_types_string.go

@@ -0,0 +1,66 @@
+// Code generated by "stringer -type=cellStatus,responseType,dirType -output=15_types_string.go"; DO NOT EDIT.
+
+package days
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[cellStatusUnknown-0]
+	_ = x[cellStatusWall-1]
+	_ = x[cellStatusOpen-2]
+	_ = x[cellStatusGoal-3]
+}
+
+const _cellStatus_name = "cellStatusUnknowncellStatusWallcellStatusOpencellStatusGoal"
+
+var _cellStatus_index = [...]uint8{0, 17, 31, 45, 59}
+
+func (i cellStatus) String() string {
+	if i < 0 || i >= cellStatus(len(_cellStatus_index)-1) {
+		return "cellStatus(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _cellStatus_name[_cellStatus_index[i]:_cellStatus_index[i+1]]
+}
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[responseWall-0]
+	_ = x[responseSuccess-1]
+	_ = x[responseFoundGoal-2]
+}
+
+const _responseType_name = "responseWallresponseSuccessresponseFoundGoal"
+
+var _responseType_index = [...]uint8{0, 12, 27, 44}
+
+func (i responseType) String() string {
+	if i < 0 || i >= responseType(len(_responseType_index)-1) {
+		return "responseType(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _responseType_name[_responseType_index[i]:_responseType_index[i+1]]
+}
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[dirNorth-1]
+	_ = x[dirSouth-2]
+	_ = x[dirWest-3]
+	_ = x[dirEast-4]
+}
+
+const _dirType_name = "dirNorthdirSouthdirWestdirEast"
+
+var _dirType_index = [...]uint8{0, 8, 16, 23, 30}
+
+func (i dirType) String() string {
+	i -= 1
+	if i < 0 || i >= dirType(len(_dirType_index)-1) {
+		return "dirType(" + strconv.FormatInt(int64(i+1), 10) + ")"
+	}
+	return _dirType_name[_dirType_index[i]:_dirType_index[i+1]]
+}

days/template.go

@@ -1,14 +1,16 @@
 package days
 
 import (
-	"parnic.com/aoc2019/utilities"
+	"fmt"
+
+	u "parnic.com/aoc2019/utilities"
 )
 
 type DayTemplate struct {
 }
 
 func (d *DayTemplate) Parse() {
-	utilities.GetIntLines("Templatep")
+	u.GetIntLines("Templatep")
 }
 
 func (d DayTemplate) Num() int {
@@ -16,9 +18,9 @@ func (d DayTemplate) Num() int {
 }
 
 func (d *DayTemplate) Part1() string {
-	return ""
+	return fmt.Sprintf("%s%d%s", u.TextBold, 0, u.TextReset)
 }
 
 func (d *DayTemplate) Part2() string {
-	return ""
+	return fmt.Sprintf("%s%d%s", u.TextBold, 0, u.TextReset)
 }

inputs/14p.txt

@@ -1,60 +1,56 @@
-11 RVCS => 8 CBMDT
-29 QXPB, 8 QRGRH => 8 LGMKD
-3 VPRVD => 6 PMFZG
-1 CNWNQ, 11 MJVXS => 6 SPLM
-13 SPDRZ, 13 PMFZG => 2 BLFM
-8 QWPFN => 7 LWVB
-1 SPLM => 8 TKWQ
-2 QRGRH, 6 CNWNQ => 7 DTZW
-2 DMLT, 1 SPLM, 1 TMDK => 9 NKNS
-1 MJVXS, 1 HLBV => 7 PQCQH
-1 JZHZP, 9 LWVB => 7 MJSCQ
-29 DGFR => 7 QRGRH
-14 XFLKQ, 2 NKNS, 4 KMNJF, 3 MLZGQ, 7 TKWQ, 24 WTDW, 11 CBMDT => 4 GJKX
-4 TKWQ, 1 WLCFR => 4 PDKGT
-2 NKNS => 4 GDKL
-4 WRZST => 9 XFLKQ
-19 DGFR => 4 VPRVD
-10 MJSCQ, 4 QWPFN, 4 QXPB => 2 MLZGQ
-1 JZHZP => 7 QWPFN
-1 XFLKQ => 9 FQGVL
-3 GQGXC => 9 VHGP
-3 NQZTV, 1 JZHZP => 2 NVZWL
-38 WLCFR, 15 GJKX, 44 LGMKD, 2 CBVXG, 2 GDKL, 77 FQGVL, 10 MKRCZ, 29 WJQD, 33 BWXGC, 19 PQCQH, 24 BKXD => 1 FUEL
-102 ORE => 5 DGFR
-17 NWKLB, 1 SBPLK => 5 HRQM
-3 BWXGC => 8 TQDP
-1 TQDP => 2 PSZDZ
-2 MJVXS => 9 WNXG
-2 NBTW, 1 HRQM => 2 SVHBH
-8 CNWNQ, 1 DTZW => 4 RVCS
-4 VHGP, 20 WNXG, 2 SVHBH => 3 SPDRZ
-110 ORE => 5 TXMC
-10 QRGRH => 5 NWKLB
-1 SBPLK => 3 MJVXS
-9 DGFR => 5 RFSRL
-5 LBTV => 3 DMLT
-1 NWKLB, 1 KMNJF, 1 HDQXB, 6 LBTV, 2 PSZDZ, 34 PMFZG, 2 SVHBH => 2 WJQD
-1 RVCS => 5 MKRCZ
-14 NQZTV, 3 FPLT, 1 SJMS => 2 GQGXC
-18 RFSRL, 13 VHGP, 23 NBTW => 5 WTDW
-1 VHGP, 6 TKWQ => 7 QXPB
-1 JZHZP, 1 CNWNQ => 5 KMNJF
-109 ORE => 9 BWXGC
-2 CNWNQ, 1 PDKGT, 2 KMNJF => 5 HDQXB
-1 PDKGT, 18 WRZST, 9 MJSCQ, 3 VHGP, 1 BLFM, 1 LGMKD, 7 WLCFR => 2 BKXD
-11 MLJK => 6 FPLT
-8 DGFR, 2 TXMC, 3 WJRC => 9 SJMS
-2 SBPLK => 1 LBTV
-22 QWPFN => 4 WRZST
-5 WRZST, 22 WNXG, 1 VHGP => 7 NBTW
-7 RVCS => 9 TMDK
-1 DGFR, 14 TXMC => 5 JZHZP
-2 JZHZP => 3 SBPLK
-19 PDKGT => 8 HLBV
-195 ORE => 6 WJRC
-6 GQGXC => 8 CNWNQ
-1 NVZWL, 4 GQGXC => 2 CBVXG
-1 NVZWL, 1 KMNJF => 8 WLCFR
-153 ORE => 4 MLJK
-1 BWXGC => 6 NQZTV
+6 WBVJ, 16 CDVNK => 2 PJBZT
+135 ORE => 8 MWDXJ
+27 NBRHT, 2 NSWK, 2 CMHMQ, 29 NFCB, 11 KNGJ, 12 MGCKC, 56 NHTKL, 7 WNFSV => 1 FUEL
+1 SFJFX, 3 MXNK => 4 NLSBZ
+2 PFKRW, 1 VXFRX, 22 QDJCL => 6 GBDG
+7 TSTF, 4 ZLJN => 7 DMWS
+5 KPCF, 1 DLMDJ, 1 FNWGH => 6 TSTF
+8 DTWKS, 1 GBDG => 4 CGZQ
+26 CNWZM, 4 KPCF => 3 DTWKS
+1 JVLHM, 7 DTWKS, 7 PJBZT => 8 MRPHV
+2 MWDXJ => 3 VHFPC
+1 WXNW, 6 PFKRW => 7 ZVGVP
+2 ZVGVP => 1 CMHMQ
+8 JVLHM, 11 XRKN, 1 HCGKZ => 8 CHZLX
+20 TSTF => 4 XDZMZ
+3 CMHMQ, 7 ZVGVP, 10 XRKN => 9 FNWGH
+12 HCGKZ, 4 NLSBZ, 15 RWRDP, 4 MRPHV, 31 KRDV, 6 PMXK, 2 NFVZ => 7 KNGJ
+1 TXZCM => 9 BMPJ
+2 ZFXQ => 3 NBRHT
+13 JVLHM, 1 VHFPC => 3 PBJPZ
+7 HCGKZ => 7 PMXK
+2 RWRDP, 3 VSTQ, 12 PMXK => 7 MXNK
+1 PJBZT, 3 QRSK => 1 KRDV
+1 MGCKC, 6 CMHMQ => 6 PQTVS
+1 TNHCS, 24 ZLJN => 4 RWRDP
+5 MWDXJ, 1 WXNW => 9 QBCLF
+1 ZFXQ, 1 DLMDJ => 4 DJXRM
+1 ZFXQ => 2 CNWZM
+1 KPCF => 6 ZXDVF
+2 MRPHV => 1 GSTG
+5 BMPJ, 2 ZLJN => 8 XQJZ
+1 MWDXJ, 1 ZVGVP => 3 CDVNK
+3 NFCB, 3 CMHMQ, 1 MWDXJ => 4 XRKN
+1 WXNW, 1 TXZCM => 5 ZLJN
+4 ZXDVF => 4 WBVJ
+2 GBDG => 4 KPCF
+4 CHZLX, 7 ZFXQ, 14 PQTVS => 9 VSTQ
+3 TXZCM, 7 ZLJN, 7 ZXDVF => 9 JVLHM
+1 DMWS, 3 TSTF => 5 HCGKZ
+2 CGZQ => 4 NFVZ
+2 PQTVS, 9 VMNJ => 9 TXZCM
+3 KPCF => 4 DLMDJ
+7 VMNJ, 24 XQJZ, 7 GSTG, 8 NLSBZ, 10 MGCKC, 2 SFJFX, 18 BMPJ => 1 NSWK
+41 CNWZM, 5 DJXRM, 1 QRSK, 1 KPCF, 15 XDZMZ, 3 MRPHV, 1 NLSBZ, 9 KRDV => 2 WNFSV
+10 PBJPZ, 29 BMPJ, 2 PMXK => 7 SFJFX
+116 ORE => 4 WXNW
+2 CNWZM => 2 TNHCS
+10 QBCLF => 7 NFCB
+1 QBCLF => 2 ZFXQ
+15 ZLJN => 7 QRSK
+183 ORE => 3 QDJCL
+11 GBDG => 5 VMNJ
+4 DMWS, 3 QRSK => 3 NHTKL
+124 ORE => 6 VXFRX
+1 MWDXJ => 6 MGCKC
+108 ORE => 9 PFKRW

inputs/15p.txt

@@ -0,0 +1 @@
+3,1033,1008,1033,1,1032,1005,1032,31,1008,1033,2,1032,1005,1032,58,1008,1033,3,1032,1005,1032,81,1008,1033,4,1032,1005,1032,104,99,1002,1034,1,1039,1001,1036,0,1041,1001,1035,-1,1040,1008,1038,0,1043,102,-1,1043,1032,1,1037,1032,1042,1105,1,124,102,1,1034,1039,1001,1036,0,1041,1001,1035,1,1040,1008,1038,0,1043,1,1037,1038,1042,1106,0,124,1001,1034,-1,1039,1008,1036,0,1041,1002,1035,1,1040,1002,1038,1,1043,101,0,1037,1042,1106,0,124,1001,1034,1,1039,1008,1036,0,1041,101,0,1035,1040,1002,1038,1,1043,101,0,1037,1042,1006,1039,217,1006,1040,217,1008,1039,40,1032,1005,1032,217,1008,1040,40,1032,1005,1032,217,1008,1039,37,1032,1006,1032,165,1008,1040,9,1032,1006,1032,165,1101,2,0,1044,1105,1,224,2,1041,1043,1032,1006,1032,179,1101,1,0,1044,1106,0,224,1,1041,1043,1032,1006,1032,217,1,1042,1043,1032,1001,1032,-1,1032,1002,1032,39,1032,1,1032,1039,1032,101,-1,1032,1032,101,252,1032,211,1007,0,50,1044,1106,0,224,1102,0,1,1044,1105,1,224,1006,1044,247,1001,1039,0,1034,102,1,1040,1035,102,1,1041,1036,101,0,1043,1038,102,1,1042,1037,4,1044,1106,0,0,37,22,74,27,37,99,30,8,72,31,49,29,51,32,85,21,39,72,2,2,43,94,31,11,76,43,95,21,38,8,90,13,39,97,54,47,14,6,20,49,5,30,97,9,99,64,71,24,36,87,52,94,36,18,52,42,83,38,98,53,26,87,69,32,18,94,2,93,97,15,65,65,21,40,99,19,91,13,4,89,38,70,65,41,73,49,62,54,37,46,14,49,88,86,13,89,23,89,10,3,48,57,92,43,65,4,35,97,48,10,19,64,3,79,38,87,6,13,71,49,74,43,92,8,4,71,6,35,85,98,94,6,38,59,80,65,46,62,63,62,49,61,68,6,7,64,66,40,56,82,59,30,85,45,57,36,86,70,25,83,31,96,65,19,16,67,55,36,49,54,29,75,69,3,3,37,75,49,23,65,22,6,52,75,31,7,87,85,19,48,97,65,51,78,10,35,40,59,54,14,85,6,30,94,68,42,87,46,75,26,82,36,21,65,90,16,59,14,76,55,37,41,99,80,9,79,12,59,17,75,2,40,52,45,76,45,16,82,13,55,61,14,11,49,97,81,99,38,35,20,98,51,64,13,24,85,94,38,25,87,1,42,89,18,32,54,55,17,15,84,98,25,31,21,55,44,57,59,11,78,49,72,87,20,7,33,91,80,75,18,33,37,52,7,26,87,65,36,52,92,6,8,95,89,37,38,57,25,23,71,75,47,20,87,90,37,54,38,77,32,39,67,16,69,62,15,96,47,91,95,18,96,24,45,21,64,9,72,2,54,65,39,36,54,23,71,74,18,26,97,35,44,29,87,54,48,31,55,33,85,74,13,99,82,39,35,97,43,20,62,58,86,98,41,47,92,79,74,10,85,28,66,86,18,35,5,84,67,13,91,47,44,1,84,56,32,96,7,77,21,88,92,38,31,65,82,87,45,55,4,60,58,64,49,53,3,63,32,52,43,10,66,75,96,53,11,95,44,36,16,65,91,47,32,9,3,73,29,25,93,29,18,88,45,41,46,12,94,13,89,5,36,94,88,33,10,10,2,52,90,19,63,26,84,12,76,16,42,75,63,39,32,72,72,84,70,2,63,33,74,43,68,38,84,72,44,89,18,24,78,69,4,80,41,54,75,72,4,16,91,5,48,30,64,38,4,52,38,30,95,99,32,38,52,35,58,71,38,89,86,25,84,88,41,39,32,56,79,12,52,19,80,46,66,38,32,69,67,6,87,88,36,59,51,5,33,46,45,82,15,57,80,91,12,86,29,34,15,61,19,73,46,82,60,73,13,52,36,67,3,49,87,39,12,98,58,87,32,82,47,65,6,87,71,13,17,65,69,14,34,42,82,42,1,77,63,10,63,28,90,24,13,99,19,38,68,62,44,2,65,81,95,7,54,24,58,16,58,48,95,9,80,9,51,73,23,96,49,64,58,1,6,72,69,39,2,10,63,36,9,85,59,90,41,2,72,77,23,23,80,75,33,6,20,18,59,39,36,89,35,89,42,42,22,37,24,30,51,53,43,78,48,27,76,84,22,81,72,25,95,28,15,51,58,48,7,1,90,72,19,37,52,60,39,81,20,70,6,39,82,26,77,14,96,52,30,84,33,66,80,5,52,15,72,46,55,2,21,8,97,79,43,8,91,27,67,5,18,74,71,34,51,6,83,25,52,92,5,15,85,11,72,33,85,30,59,6,84,29,51,77,99,43,95,44,83,95,89,27,54,16,85,90,82,34,98,59,87,12,73,25,74,29,95,82,51,5,81,46,51,0,0,21,21,1,10,1,0,0,0,0,0,0

main.go

@@ -45,6 +45,7 @@ var dayMap = []day{
 	&days.Day12{},
 	&days.Day13{},
 	&days.Day14{},
+	&days.Day15{},
 }
 
 func main() {

utilities/intcode.go

@@ -27,6 +27,7 @@ type IntcodeProgram struct {
 	memory        []int64
 	program       []int64
 	relativeBase  int
+	haltRequested bool
 }
 
 type IntcodeProgramState struct {
@@ -141,7 +142,7 @@ func (p *IntcodeProgram) RunIn(inputFunc ProvideInputFunc, outputFunc ReceiveOut
 	p.init()
 
 	inputsRequested := 0
-	for instructionPointer := 0; instructionPointer < len(p.program); {
+	for instructionPointer := 0; instructionPointer < len(p.program) && !p.haltRequested; {
 		instruction := p.GetMemory(instructionPointer)
 		instructionPointer++
 
@@ -247,4 +248,10 @@ func (p *IntcodeProgram) RunIn(inputFunc ProvideInputFunc, outputFunc ReceiveOut
 			panic(fmt.Sprintf("exception executing program - unhandled opcode %d", opcode))
 		}
 	}
+
+	p.haltRequested = false
+}
+
+func (p *IntcodeProgram) Stop() {
+	p.haltRequested = true
 }

utilities/math.go

@@ -1,5 +1,7 @@
 package utilities
 
+import "math"
+
 func GCD[T Integer](a, b T) T {
 	if b == 0 {
 		return a
@@ -25,3 +27,23 @@ func LCM[T Integer](nums ...T) uint64 {
 func lcm[T Integer](a, b T) uint64 {
 	return uint64(a*b) / uint64(GCD(a, b))
 }
+
+func Min[T Number](nums ...T) T {
+	numNums := len(nums)
+	if numNums == 2 {
+		return T(math.Min(float64(nums[0]), float64(nums[1])))
+	}
+
+	if numNums == 0 {
+		return 0
+	}
+
+	least := nums[0]
+	for i := 1; i < numNums; i++ {
+		if nums[i] < least {
+			least = nums[i]
+		}
+	}
+
+	return least
+}

utilities/permutations.go

@@ -4,7 +4,7 @@ type Permutable interface {
 	~int | ~int8 | ~int16 | ~int32 | ~int64 | ~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64
 }
 
-func GetPermutations[T Permutable](arr []T) [][]T {
+func GetPermutations[T Permutable](arr ...T) [][]T {
 	var helper func([]T, int)
 	res := [][]T{}