2021 day23, its slow... but it works :) lots of small bugs that got hunted via tests

.gitignore

@@ -3,3 +3,6 @@ input*.txt
 !scripts/skeleton/tmpls/input.txt
 prompt.md
 prompt.txt
+
+// ignore files that are prefixed with an underscore
+_*

2021/day23/main.go

@@ -28,20 +28,40 @@ func main() {
 	flag.Parse()
 	fmt.Println("Running part", part)
 
-	if part == 1 {
+	ans := amphipodDay23(input, part)
-		ans := part1(input)
+	util.CopyToClipboard(fmt.Sprintf("%v", ans))
-		util.CopyToClipboard(fmt.Sprintf("%v", ans))
+	fmt.Println("Output:", ans)
-		fmt.Println("Output:", ans)
-	} else {
-		ans := part2(input)
-		util.CopyToClipboard(fmt.Sprintf("%v", ans))
-		fmt.Println("Output:", ans)
-	}
 }
 
-func part1(input string) int {
+var roomCoordToWantCharPart1 = map[[2]int]string{
+	{2, 3}: "A", {3, 3}: "A",
+	{2, 5}: "B", {3, 5}: "B",
+	{2, 7}: "C", {3, 7}: "C",
+	{2, 9}: "D", {3, 9}: "D",
+}
+var roomCoordToWantCharPart2 = map[[2]int]string{
+	{2, 3}: "A", {3, 3}: "A", {4, 3}: "A", {5, 3}: "A",
+	{2, 5}: "B", {3, 5}: "B", {4, 5}: "B", {5, 5}: "B",
+	{2, 7}: "C", {3, 7}: "C", {4, 7}: "C", {5, 7}: "C",
+	{2, 9}: "D", {3, 9}: "D", {4, 9}: "D", {5, 9}: "D",
+}
+
+func amphipodDay23(input string, part int) int {
 	start := parseInput(input)
 
+	roomCoordToWantChar := roomCoordToWantCharPart1
+	if part == 2 {
+		roomCoordToWantChar = roomCoordToWantCharPart2
+
+		// update the grid with the 2 new rows, move old ones down
+		start.grid = append(start.grid, nil, nil)
+		start.grid[6] = start.grid[4]
+		start.grid[5] = start.grid[3]
+
+		start.grid[3] = strings.Split("  #D#C#B#A#  ", "")
+		start.grid[4] = strings.Split("  #D#B#A#C#  ", "")
+	}
+
 	minHeap := heap.NewMinHeap()
 
 	minHeap.Add(start)
@@ -53,22 +73,16 @@ func part1(input string) int {
 		if seenGrids[key] {
 			continue
 		}
-		fmt.Println(minHeap.Length(), "\n", front)
 		seenGrids[key] = true
 
-		if front.allDone() {
+		if front.allDone(roomCoordToWantChar) {
 			return front.energyUsed
 		}
 
-		unsettledCoords := front.getUnsettledCoords()
+		unsettledCoords := front.getUnsettledCoords(roomCoordToWantChar)
 		for _, unsettledCoord := range unsettledCoords {
-			// // do not try to move the last one that was moved, otherwise it'll infinite loop
-			// if front.coordOfLastMoved == unsettledCoord {
-			// 	continue
-			// }
-
 			ur, uc := unsettledCoord[0], unsettledCoord[1]
-			nextMoves := front.getNextPossibleMoves(unsettledCoord)
+			nextMoves := front.getNextPossibleMoves(unsettledCoord, roomCoordToWantChar)
 			for _, nextCoord := range nextMoves {
 				nr, nc := nextCoord[0], nextCoord[1]
 				if front.grid[nr][nc] != "." {
@@ -80,7 +94,6 @@ func part1(input string) int {
 				cp.energyUsed += calcEnergy(cp.grid[ur][uc], unsettledCoord, nextCoord)
 				cp.path += fmt.Sprintf("%s%v->%v{%d},", front.grid[ur][uc], unsettledCoord, nextCoord, cp.energyUsed)
 				cp.grid[nr][nc], cp.grid[ur][uc] = cp.grid[ur][uc], cp.grid[nr][nc]
-				cp.coordOfLastMoved = nextCoord
 
 				// add it to the min heap
 				minHeap.Add(cp)
@@ -88,23 +101,26 @@ func part1(input string) int {
 		}
 	}
 
-	// 10901 TOO LOW
-
 	panic("should return from loop")
 }
 
-func part2(input string) int {
-	return 0
-}
-
 type state struct {
-	grid             [][]string
+	grid       [][]string
-	coordOfLastMoved [2]int // store so you don't try to move the same one twice in a row
+	energyUsed int
-	energyUsed       int
+	path       string // for debugging
-	path             string
 }
 
-// Value is to implement the heap.Node interface so I can dump states into a Min Heap
+func parseInput(input string) *state {
+	grid := [][]string{}
+	for _, line := range strings.Split(input, "\n") {
+		grid = append(grid, strings.Split(line, ""))
+	}
+	return &state{
+		grid: grid,
+	}
+}
+
+// Value is to implement the heap.heapNode interface so I can dump states into a Min Heap
 func (s *state) Value() int {
 	return s.energyUsed
 }
@@ -118,7 +134,7 @@ func (s *state) String() string {
 		sb.WriteRune('\n')
 	}
 
-	sb.WriteString(fmt.Sprintf("nrg: %d, last_moved: %v, path: %s\n", s.energyUsed, s.coordOfLastMoved, s.path))
+	sb.WriteString(fmt.Sprintf("nrg: %d, ,path: %s\n", s.energyUsed, s.path))
 
 	return sb.String()
 }
@@ -126,10 +142,9 @@ func (s *state) String() string {
 // copy method to generate copies to make future heap nodes
 func (s *state) copy() *state {
 	cp := state{
-		grid:             make([][]string, len(s.grid)),
+		grid:       make([][]string, len(s.grid)),
-		coordOfLastMoved: s.coordOfLastMoved,
+		energyUsed: s.energyUsed,
-		energyUsed:       s.energyUsed,
+		path:       s.path,
-		path:             s.path,
 	}
 
 	// need to directly copy grid or else underlying arrays will be the same & interfere
@@ -141,14 +156,7 @@ func (s *state) copy() *state {
 	return &cp
 }
 
-var roomCoordToWantChar = map[[2]int]string{
+func (s *state) allDone(roomCoordToWantChar map[[2]int]string) bool {
-	{2, 3}: "A", {3, 3}: "A",
-	{2, 5}: "B", {3, 5}: "B",
-	{2, 7}: "C", {3, 7}: "C",
-	{2, 9}: "D", {3, 9}: "D",
-}
-
-func (s *state) allDone() bool {
 	for coord, want := range roomCoordToWantChar {
 		if s.grid[coord[0]][coord[1]] != want {
 			return false
@@ -157,45 +165,36 @@ func (s *state) allDone() bool {
 	return true
 }
 
-func (s *state) getUnsettledCoords() [][2]int {
+func (s *state) getUnsettledCoords(roomCoordToWantChar map[[2]int]string) [][2]int {
 	var unsettled [][2]int
-	for r, row := range s.grid {
+	// check entire hallway
-		for c, v := range row {
+	for col := 1; col < len(s.grid[0]); col++ {
-			// iterate through the entire grid, for every letter "/[A-D]/"
+		if strings.Contains("ABCD", s.grid[1][col]) {
-			if strings.Contains("ABCD", v) {
+			unsettled = append(unsettled, [2]int{1, col})
-				// add it to the unsettled list
+		}
-				coord := [2]int{r, c}
+	}
-				// IF not in coords map
-				if want, ok := roomCoordToWantChar[coord]; !ok {
-					unsettled = append(unsettled, coord)
-					continue // these are all probably unnecessary but helpful for my brain
-				} else {
-					// IF in coords map but not matching the wantChar
-					if want != v {
-						unsettled = append(unsettled, coord)
-						continue
-					} else {
-						// IF it matches wantChar but the cell below is
-						// ALSO in coords->want map AND it is the wrong want unsettledChar
-						// this means that it is in the right place but needs to get out
-						// of the way for a cell below
-						below := [2]int{r + 1, c}
-						wantBelow, ok := roomCoordToWantChar[below]
-						// ok means that it is a "room" cell, not wall
-						if ok && wantBelow != s.grid[r+1][c] {
-							unsettled = append(unsettled, coord)
-							continue
-						}
-					}
-				}
 
+	for _, col := range []int{3, 5, 7, 9} {
+		roomFullFromBack := true
+		for row := len(s.grid) - 2; row >= 2; row-- {
+			coord := [2]int{row, col}
+			wantChar := roomCoordToWantChar[coord]
+			gotChar := s.grid[row][col]
+			if gotChar != "." {
+				if gotChar != wantChar {
+					roomFullFromBack = false
+					unsettled = append(unsettled, coord)
+				} else if gotChar == wantChar && !roomFullFromBack {
+					// need to get out of the way of someone in the wrong room
+					unsettled = append(unsettled, coord)
+				}
 			}
 		}
 	}
 	return unsettled
 }
 
-// cannot stop in front of a room
+// cannot stop in front of a room, still applicable for part2
 var coordsInFrontOfRooms = map[[2]int]bool{
 	{1, 3}: true,
 	{1, 5}: true,
@@ -207,7 +206,7 @@ func isInHallway(coord [2]int) bool {
 	return coord[0] == 1
 }
 
-func (s *state) getNextPossibleMoves(unsettledCoord [2]int) [][2]int {
+func (s *state) getNextPossibleMoves(unsettledCoord [2]int, roomCoordToWantChar map[[2]int]string) [][2]int {
 	// get all the eligible locations for this coord to go to
 	unsettledChar := s.grid[unsettledCoord[0]][unsettledCoord[1]]
 
@@ -215,10 +214,10 @@ func (s *state) getNextPossibleMoves(unsettledCoord [2]int) [][2]int {
 		panic("unexpected character to get next moves for " + unsettledChar)
 	}
 
-	startedInHallway := isInHallway(unsettledCoord)
-	// fmt.Println(unsettledChar, unsettledCoord, "in hallway", startedInHallway)
 	var possible [][2]int
 
+	startedInHallway := isInHallway(unsettledCoord)
+
 	queue := [][2]int{unsettledCoord}
 	seen := map[[2]int]bool{}
 	for len(queue) > 0 {
@@ -243,26 +242,26 @@ func (s *state) getNextPossibleMoves(unsettledCoord [2]int) [][2]int {
 				} else if wantChar == unsettledChar {
 					// found the correct room
 					// check if there is a deeper part of the room (aka lower)
-					maybeLower := [2]int{front[0] + 1, front[1]}
+
-					if _, ok := roomCoordToWantChar[maybeLower]; ok {
+					// if there is a "stuck" amphipod deeper in the room, cannot stop here
-						lowerChar := s.grid[maybeLower[0]][maybeLower[1]]
+					// if not deepest empty coord, cannot stop here
-						if lowerChar == "." {
+					// in both cases walking further is handles all cases, whether that's
-							possible = append(possible, maybeLower)
+					//   to walk further in or out of the room
-							// can only go deeper into the room so just kill the traverse here
+					isStuckAmphipod := false
-							continue
+					roomHasDeeperOpenSpaces := false
+					for r := front[0] + 1; r < len(s.grid)-1; r++ {
+						char := s.grid[r][front[1]]
+						if char == "." {
+							roomHasDeeperOpenSpaces = true
 						}
-						// if lower char is the same, then can move into the front of the room
+						if char != "." && char != unsettledChar {
-						if lowerChar == unsettledChar {
+							isStuckAmphipod = true
-							possible = append(possible, front)
+							break
-							// no where else to go, so just continue and end this iteration
-							continue
 						}
-					} else {
+					}
-						// otherwise already deep part of the room, append it
+
-						// ?probably unreachable code
+					if !roomHasDeeperOpenSpaces && !isStuckAmphipod {
-						fmt.Println("unreachable code in else block?")
 						possible = append(possible, front)
-						continue
 					}
 				}
 			}
@@ -306,24 +305,3 @@ func calcEnergy(char string, start, end [2]int) int {
 	}
 	return energyPerType[char] * dist
 }
-
-func parseInput(input string) *state {
-	grid := [][]string{}
-	for _, line := range strings.Split(input, "\n") {
-		grid = append(grid, strings.Split(line, ""))
-	}
-
-	// // uncomment to check if coordToWantChars are correct...
-	// for c, unsettledChar := range roomCoordToWantChar {
-	// 	grid[c[0]][c[1]] = unsettledChar
-	// }
-	// st := state{grid: grid}
-	// fmt.Println(st.String())
-	// if !st.allDone() {
-	// 	panic("state.allDone() should be true ")
-	// }
-
-	return &state{
-		grid: grid,
-	}
-}

2021/day23/main_test.go

@@ -2,7 +2,9 @@ package main
 
 import (
 	_ "embed"
+	"fmt"
 	"reflect"
+	"strings"
 	"testing"
 )
 
@@ -18,96 +20,94 @@ var doneInput = `#############
   #A#B#C#D#  
   #########  `
 
-func Test_part1(t *testing.T) {
+func Test_amphipodDay23(t *testing.T) {
 	tests := []struct {
 		name  string
 		input string
+		part  int
 		want  int
 	}{
 		{
-			name:  "example",
+			name:  "part1 example",
 			input: example,
+			part:  1,
 			want:  12521,
 		},
 		{
-			name: "simple",
+			name: "part1 simple",
 			input: `#############
 #.A.........#
 ###.#B#C#D###
   #A#B#C#D#
   #########  `,
+			part: 1,
 			want: 2,
 		},
 		{
-			name: "simple: A then B",
+			name: "part1 simple: A then B",
 			input: `#############
 #BA.........#
 ###.#.#C#D###
   #A#B#C#D#
   #########  `,
+			part: 1,
 			want: 52,
 		},
 		{
 			// NOTE found a bug! A moving from a deep room to another room is calculating energy
 			// NOTE as if it is walking through the wall
-			name: "reversed B room", // B has to get out of A's way first
+			name: "part1 reversed B room", // B has to get out of A's way first
 			input: `#############
 #.B.........#
 ###.#B#C#D###
   #A#A#C#D#
   #########  `,
+			part: 1,
 			want: 95,
 		},
 		{
-			name: "some shuffling",
+			name: "part1 some shuffling",
 			input: `#############
 #...........#
 ###A#B#C#D###
   #A#C#B#D#
   #########  `,
+			part: 1,
 			want: 1120,
 		},
 		{
-			name:  "doneInput",
+			name:  "part1 doneInput",
 			input: doneInput,
+			part:  1,
 			want:  0,
 		},
 		{
-			name:  "actual",
+			name:  "part1 actual",
 			input: input,
+			part:  1,
 			want:  15299,
 		},
-	}
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			if got := part1(tt.input); got != tt.want {
-				t.Errorf("part1() = %v, want %v", got, tt.want)
-			}
-		})
-	}
-}
 
-func Test_part2(t *testing.T) {
-	tests := []struct {
-		name  string
-		input string
-		want  int
-	}{
 		{
-			name:  "example",
+			name:  "example part 2",
 			input: example,
+			part:  2,
 			want:  44169,
 		},
-		// {
+		{
-		// 	name:  "actual",
+			name:  "part2 actual",
-		// 	input: input,
+			input: input,
-		// 	want:  0,
+			part:  2,
-		// },
+			want:  47193,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			if got := part2(tt.input); got != tt.want {
+			if testing.Short() && strings.Contains(tt.name, "actual") {
-				t.Errorf("part2() = %v, want %v", got, tt.want)
+				t.Skip(fmt.Sprintf("skipping %q in -short mode", tt.name))
+			}
+			if got := amphipodDay23(tt.input, tt.part); got != tt.want {
+				t.Errorf("amphipodDay23() = %v, want %v", got, tt.want)
 			}
 		})
 	}
@@ -115,14 +115,16 @@ func Test_part2(t *testing.T) {
 
 func Test_state_getUnsettledCoords(t *testing.T) {
 	tests := []struct {
-		name  string
+		name                string
-		input string
+		input               string
-		want  [][2]int
+		roomCoordToWantChar map[[2]int]string
+		want                [][2]int
 	}{
 		{
-			name:  "already done",
+			name:                "already done",
-			input: doneInput,
+			input:               doneInput,
-			want:  nil,
+			roomCoordToWantChar: roomCoordToWantCharPart1,
+			want:                nil,
 		},
 		{
 			name:  "example - 2 \"done\" amphipods",
@@ -134,22 +136,41 @@ func Test_state_getUnsettledCoords(t *testing.T) {
 				  #A#D#C#A#
 				  #########
 			*/
-			want: [][2]int{{2, 3}, {2, 5}, {2, 7}, {2, 9}, {3, 5}, {3, 9}},
+			roomCoordToWantChar: roomCoordToWantCharPart1,
+			want:                [][2]int{{2, 3}, {3, 5}, {2, 5}, {2, 7}, {3, 9}, {2, 9}},
 		},
 		{
 			name: "four unsettled coords",
-			input: ` #############
+			input: `#############
 #AB.....D..D#
 ###.#.#C#.###
   #A#B#C#.#  
-  ######### `,
+  #########  `,
-			want: [][2]int{{1, 1}, {1, 2}, {1, 8}, {1, 11}},
+			roomCoordToWantChar: roomCoordToWantCharPart1,
+			want:                [][2]int{{1, 1}, {1, 2}, {1, 8}, {1, 11}},
+		},
+		{
+			name: "part2 test",
+			input: `#############
+#AB.....D..D#
+###.#.#C#.###
+  #A#A#C#.#  
+  #B#B#C#D#  
+  #A#B#C#D#  
+  #########  `,
+			roomCoordToWantChar: roomCoordToWantCharPart2,
+			want: [][2]int{
+				// hallway
+				{1, 1}, {1, 2}, {1, 8}, {1, 11},
+				{4, 3}, {3, 3}, // A room
+				{3, 5}, // B room
+			},
 		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			s := parseInput(tt.input)
-			if got := s.getUnsettledCoords(); !reflect.DeepEqual(got, tt.want) {
+			if got := s.getUnsettledCoords(tt.roomCoordToWantChar); !reflect.DeepEqual(got, tt.want) {
 				t.Errorf("state.getUnsettledCoords() = %v, want %v", got, tt.want)
 			}
 		})
@@ -158,10 +179,11 @@ func Test_state_getUnsettledCoords(t *testing.T) {
 
 func Test_state_getNextPossibleMoves(t *testing.T) {
 	tests := []struct {
-		name           string
+		name                string
-		input          string
+		input               string
-		unsettledCoord [2]int
+		unsettledCoord      [2]int
-		want           [][2]int
+		roomCoordToWantChar map[[2]int]string
+		want                [][2]int
 	}{
 		{
 			name:  "example, deep room is stuck",
@@ -173,46 +195,116 @@ func Test_state_getNextPossibleMoves(t *testing.T) {
 				  #A#D#C#A#
 				  #########
 			*/
-			unsettledCoord: [2]int{3, 3}, // DEEP room in A slot
+			unsettledCoord:      [2]int{3, 3}, // DEEP room in A slot
-			want:           nil,
+			roomCoordToWantChar: roomCoordToWantCharPart1,
+			want:                nil,
 		},
 		{
-			name:           "example-frontA",
+			name:                "example-frontA",
-			input:          example,
+			input:               example,
-			unsettledCoord: [2]int{2, 3}, // FRONT room in A slot
+			unsettledCoord:      [2]int{2, 3}, // FRONT room in A slot
-			want:           [][2]int{{1, 2}, {1, 4}, {1, 1}, {1, 6}, {1, 8}, {1, 10}, {1, 11}},
+			roomCoordToWantChar: roomCoordToWantCharPart1,
+			want:                [][2]int{{1, 2}, {1, 4}, {1, 1}, {1, 6}, {1, 8}, {1, 10}, {1, 11}},
 		},
 		{
-			name:           "example-deepA-should be stuck",
+			name:                "example-deepA-should be stuck",
-			input:          example,
+			input:               example,
-			unsettledCoord: [2]int{3, 3}, // FRONT room in A slot
+			unsettledCoord:      [2]int{3, 3}, // FRONT room in A slot
-			want:           nil,
+			roomCoordToWantChar: roomCoordToWantCharPart1,
+			want:                nil,
 		},
 		{
 			name: "hallways to rooms ONLY",
-			input: ` #############
+			input: `#############
 #AB.....D..D#
 ###.#.#C#.###
   #A#B#C#.#  
   ######### `,
-			unsettledCoord: [2]int{1, 2},
+			unsettledCoord:      [2]int{1, 2},
-			want:           [][2]int{{2, 5}},
+			roomCoordToWantChar: roomCoordToWantCharPart1,
+			want:                [][2]int{{2, 5}},
 		},
 		{
 			name: "hallway to DEEP room",
-			input: ` #############
+			input: `#############
 #AB.....D..D#
 ###.#.#C#.###
   #A#B#C#.#  
   ######### `,
-			unsettledCoord: [2]int{1, 8},
+			unsettledCoord:      [2]int{1, 8},
-			want:           [][2]int{{3, 9}},
+			roomCoordToWantChar: roomCoordToWantCharPart1,
+			want:                [][2]int{{3, 9}},
+		},
+		{
+			name: "part2 simple",
+			input: `#############
+#B..........#
+###A#.#C#D###
+  #A#B#C#D#  
+  #A#B#C#D#  
+  #A#B#C#D#  
+  ######### `,
+			unsettledCoord:      [2]int{1, 1},
+			roomCoordToWantChar: roomCoordToWantCharPart2,
+			want:                [][2]int{{2, 5}},
+		},
+		{
+			name: "part2 back of room",
+			input: `#############
+#B......B.BB#
+###A#.#C#D###
+  #A#.#C#D#  
+  #A#.#C#D#  
+  #A#.#C#D#  
+  ######### `,
+			unsettledCoord:      [2]int{1, 1},
+			roomCoordToWantChar: roomCoordToWantCharPart2,
+			want:                [][2]int{{5, 5}},
+		},
+		{
+			name: "part2 back of room",
+			input: `#############
+#B......B..B#
+###A#.#C#D###
+  #A#.#C#D#  
+  #A#.#C#D#  
+  #A#B#C#D#  
+  ######### `,
+			unsettledCoord:      [2]int{1, 8},
+			roomCoordToWantChar: roomCoordToWantCharPart2,
+			want:                [][2]int{{4, 5}},
+		},
+		{
+			name: "part2 bug moving C from B room to C room",
+			input: `#############
+#AA.....B.BD#
+###B#.#.#.###
+  #D#C#.#.#  
+  #D#B#C#C#  
+  #A#D#C#A#  
+  #########  `,
+			unsettledCoord:      [2]int{3, 5},
+			roomCoordToWantChar: roomCoordToWantCharPart2,
+			want:                [][2]int{{1, 4}, {1, 6}, {3, 7}},
+		},
+		{
+			name: "part2 bug moving B out of B room bc of a blocked D",
+			input: `#############
+#AA.....B.BD#
+###B#.#.#.###
+  #D#.#C#.#  
+  #D#B#C#C#  
+  #A#D#C#A#  
+  #########  `,
+			unsettledCoord:      [2]int{4, 5},
+			roomCoordToWantChar: roomCoordToWantCharPart2,
+			want:                [][2]int{{1, 4}, {1, 6}},
 		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			s := parseInput(tt.input)
-			if got := s.getNextPossibleMoves(tt.unsettledCoord); !reflect.DeepEqual(got, tt.want) {
+			if got := s.getNextPossibleMoves(tt.unsettledCoord, tt.roomCoordToWantChar); !reflect.DeepEqual(got, tt.want) {
 				t.Errorf("state.getNextPossibleMoves() = %v, want %v", got, tt.want)
 			}
 		})
@@ -266,6 +358,15 @@ func Test_calcEnergy(t *testing.T) {
 			},
 			want: 600,
 		},
+		{
+			name: "part2 C",
+			args: args{
+				char:  "C",
+				start: [2]int{5, 11},
+				end:   [2]int{3, 7},
+			},
+			want: 1000,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {