diff --git a/day16/allbestpaths.go b/day16/allbestpaths.go new file mode 100644 index 0000000..ef1d15e --- /dev/null +++ b/day16/allbestpaths.go @@ -0,0 +1,207 @@ +package main + +import ( "os"; "fmt"; "strings") + + +// ---------------------------------------- +type Direction uint8 + +const ( + Up Direction = iota + Down Direction = iota + Left Direction = iota + Right Direction = iota +) + + +// ---------------------------------------- +type Path struct { + position [2]uint + direction Direction +} + +func (p Path) StepUnbound(d Direction) Path { + switch { + case d == Down: p.position[1]++ + case d == Up: p.position[1]-- + case d == Left: p.position[0]-- + case d == Right: p.position[0]++ + } + p.direction = d + + return p +} + + +// ---------------------------------------- +type Maze struct { + start [2]uint + end [2]uint + field [][]byte +} + +func NewMaze(str string) *Maze { + var maze Maze + + for y, line := range strings.Split(str, "\n") { + line_arr := make([]byte, len(line)) + for x, char := range []byte(line) { + switch { + case char == 'S': + line_arr[x] = '.' + maze.start = [...]uint{uint(x), uint(y)} + case char == 'E': + line_arr[x] = '.' + maze.end = [...]uint{uint(x), uint(y)} + default: line_arr[x] = char + } + } + maze.field = append(maze.field, line_arr) + } + + return &maze +} + +func (m *Maze) Step(path Path) []Path { + out := make([]Path, 0, 4) + + if m.field[path.position[1] + 1][path.position[0]] == '.' && path.direction != Up { + out = append(out, path.StepUnbound(Down)) + } + if m.field[path.position[1] - 1][path.position[0]] == '.' && path.direction != Down { + out = append(out, path.StepUnbound(Up)) + } + if m.field[path.position[1]][path.position[0] + 1] == '.' && path.direction != Left { + out = append(out, path.StepUnbound(Right)) + } + if m.field[path.position[1]][path.position[0] - 1] == '.' && path.direction != Right { + out = append(out, path.StepUnbound(Left)) + } + + return out +} + +func (m *Maze) Start() Path { + return Path{m.start, Right} +} + +func (m *Maze) Finished(path Path) bool { + return m.end == path.position +} + +func (m *Maze) Print() { + for _, line := range m.field { + fmt.Println(string(line)) + } +} + + +// ---------------------------------------- +type MazeGraph struct { + cost uint + position [2]uint + children []*MazeGraph +} + +var new_maze_graph_visited map[Path]uint + +func NewMazeGraph(m *Maze, start Path, cost uint) *MazeGraph { + children := make([]*MazeGraph, 0, 3) + + // finish reached? + if m.Finished(start) { return &MazeGraph{ cost: cost, position: start.position, children: children } } + + // check for loop + value, exists := new_maze_graph_visited[start] + if exists { + if value < cost { return nil } + } + new_maze_graph_visited[start] = cost + + // build subgraphs/ children + for _, path := range m.Step(start) { + var child *MazeGraph + if start.direction != path.direction { + child = NewMazeGraph(m, path, cost + 1001) + } else { + child = NewMazeGraph(m, path, cost + 1) + } + + if child != nil { children = append(children, child) } + } + + // found dead end + if len(children) == 0 { return nil } + + return &MazeGraph{ cost: cost, children: children, position: start.position } +} + +func (graph *MazeGraph) Leaves() []*MazeGraph { + out := make([]*MazeGraph, 0) + + if len(graph.children) == 0 { + out = append(out, graph) + return out + } + + for _, g := range graph.children { + out = append(out, g.Leaves()...) + } + return out +} + +func (graph *MazeGraph) PathsToLeaves(leave_cost uint) [][2]uint { + out := make([][2]uint, 0) + + if len(graph.children) == 0 { + // leave found + if graph.cost == leave_cost { + return append(out, graph.position) + } else { + return nil + } + } + + // collect from children + for _, g := range graph.children { + subpath := g.PathsToLeaves(leave_cost) + if subpath != nil { + out = append(out, subpath...) + } + } + // if all children returned nil + if len(out) == 0 { return nil } + + return append(out, graph.position) +} + + +// ---------------------------------------- +func check(err error) { if err != nil { panic(err) } } + +func uniq_count(slice [][2]uint) int { + m := make(map[[2]uint]bool) + for _, s := range slice { + m[s] = true + } + return len(m) +} + + +func main() { + dat, err := os.ReadFile("data.txt") + check(err) + + input := strings.TrimSpace(string(dat)) + maze := NewMaze(input) + + var best *MazeGraph + new_maze_graph_visited = make(map[Path]uint) + maze_graph := NewMazeGraph(maze, maze.Start(), 0) + + for _, leave := range maze_graph.Leaves() { + if best == nil || best.cost > leave.cost { best = leave } + } + fmt.Println(best.cost) + fmt.Println(uniq_count(maze_graph.PathsToLeaves(best.cost))) +} diff --git a/day16/data.txt b/day16/data.txt new file mode 100644 index 0000000..31204d9 --- /dev/null +++ b/day16/data.txt @@ -0,0 +1,141 @@ +############################################################################################################################################# 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diff --git a/day16/maze.go b/day16/maze.go new file mode 100644 index 0000000..7b79550 --- /dev/null +++ b/day16/maze.go @@ -0,0 +1,176 @@ +package main + +import ( "os"; "fmt"; "strings") + + +// ---------------------------------------- +type Direction uint8 + +const ( + Up Direction = iota + Down Direction = iota + Left Direction = iota + Right Direction = iota +) + + +// ---------------------------------------- +type Path struct { + position [2]uint + direction Direction +} + +func (p Path) StepUnbound(d Direction) Path { + switch { + case d == Down: p.position[1]++ + case d == Up: p.position[1]-- + case d == Left: p.position[0]-- + case d == Right: p.position[0]++ + } + p.direction = d + + return p +} + + +// ---------------------------------------- +type Maze struct { + start [2]uint + end [2]uint + field [][]byte +} + +func NewMaze(str string) *Maze { + var maze Maze + + for y, line := range strings.Split(str, "\n") { + line_arr := make([]byte, len(line)) + for x, char := range []byte(line) { + switch { + case char == 'S': + line_arr[x] = '.' + maze.start = [...]uint{uint(x), uint(y)} + case char == 'E': + line_arr[x] = '.' + maze.end = [...]uint{uint(x), uint(y)} + default: line_arr[x] = char + } + } + maze.field = append(maze.field, line_arr) + } + + return &maze +} + +func (m *Maze) Step(path Path) []Path { + out := make([]Path, 0, 4) + + if m.field[path.position[1] + 1][path.position[0]] == '.' && path.direction != Up { + out = append(out, path.StepUnbound(Down)) + } + if m.field[path.position[1] - 1][path.position[0]] == '.' && path.direction != Down { + out = append(out, path.StepUnbound(Up)) + } + if m.field[path.position[1]][path.position[0] + 1] == '.' && path.direction != Left { + out = append(out, path.StepUnbound(Right)) + } + if m.field[path.position[1]][path.position[0] - 1] == '.' && path.direction != Right { + out = append(out, path.StepUnbound(Left)) + } + + return out +} + +func (m *Maze) Start() Path { + return Path{m.start, Right} +} + +func (m *Maze) Finished(path Path) bool { + return m.end == path.position +} + + +func (m *Maze) Print() { + for _, line := range m.field { + fmt.Println(string(line)) + } +} + + +// ---------------------------------------- +type MazeGraph struct { + cost uint + children []*MazeGraph +} + +var new_maze_graph_visited map[Path]uint + +func NewMazeGraph(m *Maze, start Path, cost uint) *MazeGraph { + children := make([]*MazeGraph, 0, 3) + + // finish reached? + if m.Finished(start) { return &MazeGraph{ cost, children } } + + // check for loop + value, exists := new_maze_graph_visited[start] + if exists { + if value <= cost { return nil } + } + new_maze_graph_visited[start] = cost + + // build subgraphs/ children + for _, path := range m.Step(start) { + var child *MazeGraph + if start.direction != path.direction { + child = NewMazeGraph(m, path, cost + 1001) + } else { + child = NewMazeGraph(m, path, cost + 1) + } + + if child != nil { children = append(children, child) } + } + + // found dead end + if len(children) == 0 { return nil } + + // collapse if there is only one possible way + if len(children) == 0 { return children[0] } + + return &MazeGraph{ cost: cost, children: children } +} + +func (graph *MazeGraph) Leaves() []*MazeGraph { + out := make([]*MazeGraph, 0) + + if len(graph.children) == 0 { + out = append(out, graph) + return out + } + + for _, g := range graph.children { + out = append(out, g.Leaves()...) + } + return out +} + + +// ---------------------------------------- +func check(err error) { if err != nil { panic(err) } } + + +func main() { + dat, err := os.ReadFile("data.txt") + check(err) + + input := strings.TrimSpace(string(dat)) + maze := NewMaze(input) + + var best *MazeGraph + new_maze_graph_visited = make(map[Path]uint) + + for _, leave := range NewMazeGraph(maze, maze.Start(), 0).Leaves() { + if best == nil || best.cost > leave.cost { best = leave } + } + + fmt.Println(best.cost) +}