day10, All Is Broken

day10/dayTen.go

@@ -12,7 +12,7 @@ import (
 func Run() int {
 	fmt.Println("hello day 10")
 	// filename := "day10/example2noisy"
-	filename := "day10/input"
+	filename := "day10/example5"
 	fieldMap := Read(filename)
 	fmt.Println(fieldMap.BeastCoord)
 	// fmt.Println(fieldMap.String())
@@ -35,12 +35,15 @@ func Run() int {
 		}
 	}
 
-	fmt.Println("beore marking:")
+	// fmt.Println("beore marking:")
 	fieldMap.markMainLoop()
-	fmt.Println("after marking:")
+	// fmt.Println("after marking loop:")
-	fmt.Println(fieldMap.String())
+	// fmt.Println(fieldMap.String())
+	fmt.Println("beore marking closest Outer:")
 	// now main loop is closed with regards to 'S' neighbors
-
+	fieldMap.initialMarkOuter()
+	fmt.Println("after marking closest Outer:")
+	fmt.Println(fieldMap.String())
 	return (len / 2) + (len % 2)
 }
 
@@ -62,48 +65,68 @@ type Cell struct {
 	Tile         rune
 	Neighbords   []Coord
 	IsOnMainPath bool
+	IsOuter      bool
 }
-func (c *Cell)String() string {
+
+func (c *Cell) String() string {
 	if c.Tile == 'S' {
 		return "S"
 	}
+	if c.IsOuter {
+		return "O"
+	}
 	if !c.IsOnMainPath {
 		return " "
 	}
 	switch c.Tile {
-    case '7': return "⌝"
+	case '7':
-    case 'J': return "⌟"
+		return "⌝"
-    case 'F': return "⌜"
+	case 'J':
-    case 'L': return "⌞"
+		return "⌟"
-    case '.': return " "
+	case 'F':
-    default: return string(c.Tile)
+		return "⌜"
+	case 'L':
+		return "⌞"
+	case '.':
+		return " "
+	default:
+		return string(c.Tile)
 	}
 }
+
 type Coord struct {
 	X, Y int
 }
-func (c Coord)Equal(other Coord) bool {
+
+func (c Coord) Equal(other Coord) bool {
 	return c.X == other.X && c.Y == other.Y
 }
 
 type Direction int
-const (UP Direction = iota
+
+const (
+	UP Direction = iota
 	DOWN
 	LEFT
-	RIGHT)
+	RIGHT
+)
+func (d Direction)String() string {
+	names := []string{"UP", "DOWN", "LEFT", "RIGHT"}
+	return names[d]
+}
 
-func (c Coord)Shift(d Direction) Coord {
+func (c Coord) Shift(d Direction) Coord {
 	x, y := c.X, c.Y
 	result := Coord{}
 	switch d {
 	case UP:
-		result =  Coord{x, y-1}
+		result = Coord{x, y - 1}
 	case DOWN:
-		result =  Coord{x, y+1}
+		result = Coord{x, y + 1}
 	case LEFT:
-		result =  Coord{x-1, y}
+		result = Coord{x - 1, y}
 	case RIGHT:
-		result =  Coord{x+1, y}
+		result = Coord{x + 1, y}
 	}
 	return result
 }
@@ -113,7 +136,8 @@ type Map struct {
 	Height, Width int
 	BeastCoord    Coord
 }
-func (m *Map)String() string {
+
+func (m *Map) String() string {
 	result := ""
 	for y := 0; y < m.Height; y++ {
 		for x := 0; x < m.Width; x++ {
@@ -125,7 +149,7 @@ func (m *Map)String() string {
 	return result
 }
 
-func (m *Map)markMainLoop() {
+func (m *Map) markMainLoop() {
 	start := m.Cells[m.BeastCoord]
 	start.IsOnMainPath = true
 	m.Cells[m.BeastCoord] = start
@@ -136,7 +160,7 @@ func (m *Map)markMainLoop() {
 		currentCell.IsOnMainPath = true
 		m.Cells[currentCell.Coord] = currentCell
 		// log.Printf("marking loop on %+v (%s)\n", currentCell, currentCell.String())
-		nextCoord, err := currentCell.Next(previous.Coord)
+		nextCoord, _, err := currentCell.Next(previous.Coord)
 		// log.Printf("next coord will be %v %s\n", nextCoord, err)
 		if err != nil {
 			return
@@ -146,9 +170,114 @@ func (m *Map)markMainLoop() {
 	}
 }
 
+func (m *Map) initialMarkOuter() {
+	// for start point let's take my highest on main path and one above
+	// and will have a runner pointer to the cell on the outside
+
+	var outerRunner Cell
+	var pathCunner Cell
+outer:
+	for y := 0; y < m.Height; y++ {
+		for x := 0; x < m.Width; x++ {
+			if cell := m.Cells[Coord{x, y}]; cell.IsOnMainPath {
+				pathCunner = cell
+				outerRunner = m.Cells[Coord{x, y - 1}]
+				break outer
+			}
+		}
+	}
+	startPoint := pathCunner
+	previous := startPoint
+	firstDirection := startPoint.OutDirections()[0]
+	nextCoord := previous.Coord.Shift(firstDirection)
+	currentCell := m.Cells[nextCoord]
+	var exitingPreviousBy Direction = firstDirection
+
+	stepsToDo := 1
+	for currentCell.Coord != startPoint.Coord {
+
+		// looping once. and need to operae on the outer runner
+		// and i don't have the direction? well, i guess i could use direction
+
+		outerRunner = m.markOuterAndMove(previous, outerRunner, exitingPreviousBy)
+		var err error
+		nextCoord, exitingPreviousBy, err = currentCell.Next(previous.Coord)
+		if err != nil {
+			panic("initial mark cycle can't get next")
+		}
+		previous = currentCell
+		currentCell = m.Cells[nextCoord]
+
+		stepsToDo -= 1
+		if stepsToDo == 0 {
+			break
+		}
+	}
+}
+
+func (m *Map) markOuter(outerPointerCoord Coord) {
+	if !m.isValidCoord(outerPointerCoord) {
+		return
+	}
+	outerPointer := m.Cells[outerPointerCoord]
+	if outerPointer.IsOnMainPath {
+		return
+	}
+	outerPointer.IsOuter = true
+	m.Cells[outerPointer.Coord] = outerPointer
+}
+
+// move both inner path Cell and OuterCell through direction from inner path cell
+// and i need to know direction from which we came into 'pathPointer'
+func (m *Map) markOuterAndMove(pathPointer Cell, outerPointer Cell, exitingCurrentBy Direction) Cell {
+	// mark &save outer, get moves from pathPointer & direct
+	// do 1 or 2 moves and on each mark & save
+	m.markOuter(outerPointer.Coord)
+
+	outerPointerMovements := outerPointerMovements[pathPointer.Tile][exitingCurrentBy]
+	log.Printf("moving outer from %s exited via %s with moves %+v\n", pathPointer.String(), exitingCurrentBy.String(), outerPointerMovements)
+	coord := outerPointer.Coord
+	for _, movement := range outerPointerMovements {
+		coord = coord.Shift(movement)
+		m.markOuter(coord)
+	}
+
+	newPointer := m.Cells[coord]
+	return newPointer
+}
+
+// yeah, this is not enough. if we move down from | we could be directly up to -
+// so we need TurnLeft & TurnRight things
+var outerPointerMovements map[rune]map[Direction][]Direction = map[rune]map[Direction][]Direction{
+	'|': {
+		UP: {UP},
+		DOWN: {DOWN}, 
+	},
+	'-': {
+		LEFT: {LEFT},
+		RIGHT: {RIGHT}, 
+	},
+	'L': {
+		DOWN: {DOWN, RIGHT}, 
+		LEFT: {RIGHT, UP},
+	},
+	'J': {
+		DOWN: {DOWN, LEFT}, 
+		RIGHT: {RIGHT, UP},
+	},
+	'F': {
+		DOWN: {LEFT, DOWN}, 
+		RIGHT: {UP, RIGHT},
+	},
+	'7': {
+		RIGHT: {RIGHT, DOWN}, 
+		UP: {UP, LEFT},
+	},
+}
+
 // call for each direction from beast.
 // will run the path until it loops back at best, or terminates
-func (m *Map)checkDirectionFromBeast(through Coord) (isCycle bool, len int) {
+func (m *Map) checkDirectionFromBeast(through Coord) (isCycle bool, len int) {
 	// defer log.Printf("about to return check from beast %v, isCycle : %t. len is %d", through, isCycle, len)
 	len = 1
 	previous := m.Cells[m.BeastCoord]
@@ -157,7 +286,7 @@ func (m *Map)checkDirectionFromBeast(through Coord) (isCycle bool, len int) {
 	for found && currentCell.Tile != 'S' {
 		// log.Printf("check direction loop for %+v (%s)\n", currentCell, currentCell.String())
 		len += 1
-		nextCoord, err := currentCell.Next(previous.Coord)
+		nextCoord, _, err := currentCell.Next(previous.Coord)
 		// log.Printf("next coord will be %v %s\n", nextCoord, err)
 		if err != nil {
 			return
@@ -178,7 +307,7 @@ func (m *Map)checkDirectionFromBeast(through Coord) (isCycle bool, len int) {
 	return
 }
 
-func (m *Map)isValidCoord(c Coord) bool {
+func (m *Map) isValidCoord(c Coord) bool {
 	if c.X < 0 || c.Y < 0 || c.X >= m.Height || c.Y >= m.Width {
 		return false
 	}
@@ -228,18 +357,25 @@ func (c *Cell) GetNeighbors() []Coord {
 // - check if 'from' is in neighbors
 // if it is - then take another neighbor
 // wouldn't work for 'S' but we don't need it to
-func (c *Cell) Next(from Coord) (to Coord, err error) {
+func (c *Cell) Next(from Coord) (to Coord, cameFrom Direction, err error) {
 	if len(c.Neighbords) != 2 {
-		return Coord{}, errors.New(fmt.Sprintf("not 2 neighbors: cannot get next from %v through %c", from, c))
+		return Coord{}, 0, errors.New(fmt.Sprintf("not 2 neighbors: cannot get next from %v through %c", from, c))
 	}
 
 	i := slices.Index(c.Neighbords, from)
 	if i == -1 {
-		return Coord{}, errors.New(fmt.Sprintf("cannot find next from %v through %+v", from, c))
+		return Coord{}, 0, errors.New(fmt.Sprintf("cannot find next from %v through %+v", from, c))
+	}
+
+	var nextDirection Direction
+	for _, direction := range c.OutDirections() {
+		if c.Coord.Shift(direction) != from {
+			nextDirection = direction
+		}
 	}
 
 	otherIndex := 1 - i
-	return c.Neighbords[otherIndex], nil
+	return c.Neighbords[otherIndex], nextDirection, nil
 }
 
 // x from left to right; y from top to bottom

day10/example5

@@ -0,0 +1,7 @@
+.......
+...F7..
+..FJ|..
+.SJ.L7.
+.|F--J.
+.LJ....
+.......

day10/notes.org

@@ -18,3 +18,30 @@ but yeah, if i make initial filling in of the I, then i could just fill in all .
 and count I
 
 sounds like a plan
+** allright, i found main path, display all not on main path as ' '
+and the thing is a mess
+
+i don't know how to select a point to mark as 'I'
+
+but! if i select a point to mark as 'O'
+and then go around the main path, marking things on the side as 'O'
+then i would be able to fill in all which are neighbors of 'O' as 'O'
+and that would leave only 'I' to be counted
+
+so.
+
+how would i monitor consistent 'side' of the pipe during the walkhrough?
+if we go down - we color as 'O' one down.
+if we go angle - color two - one down and one to the right.
+and only color if it's not already on main path.
+
+i suppose so
+** so a new method for initial pass of 'O'
+well, i'll need access to the direction, in which the neighbor is taken?
+nooo. not direction, but the symbol. ok, this is easier
+
+but i'll need to mutate the field
+
+no, i do need direction.
+
+ok, let's go lunch maybe, and maybe it will be a place with a power outlet as well