updates

2024/go/day18/day18.go

@@ -0,0 +1,126 @@
+package day18
+
+import (
+	"adventofcode2024/utils"
+	"adventofcode2024/utils/dijkstra"
+	"adventofcode2024/utils/grid2d"
+	"fmt"
+	"strings"
+)
+
+type (
+	Vec  struct{ x, y int }
+	Dir  struct{ x, y int }
+	Cell rune
+	Move struct {
+		p Vec
+		d Dir
+	}
+	Maze struct {
+		height, width int
+		start         Vec
+		end           Vec
+		grid          *grid2d.Grid[Cell]
+	}
+)
+
+const (
+	WALL     Cell = '#'
+	CORRIDOR Cell = '.'
+	START    Cell = 'S'
+	END      Cell = 'E'
+	PATH     Cell = '*'
+)
+
+var (
+	NORTH      = Dir{0, -1}
+	EAST       = Dir{1, 0}
+	SOUTH      = Dir{0, 1}
+	WEST       = Dir{-1, 0}
+	DIRECTIONS = []Dir{NORTH, EAST, SOUTH, WEST}
+)
+
+func Part1(input string) int {
+	maze := Maze{}.Parse(input, 1024)
+	fmt.Println(maze)
+	data := inputGraph(*maze)
+	graph := dijkstra.CreateGraph(data)
+	path, dist := dijkstra.GetShortestPath(data.From, data.To, graph)
+	for _, p := range path {
+		maze.grid.Set(p.X, p.Y, PATH)
+	}
+	fmt.Println(maze)
+	return dist
+}
+func Part2(input string) int {
+	maze := Maze{}.Parse(input, 2877)
+	fmt.Println(maze)
+	data := inputGraph(*maze)
+	graph := dijkstra.CreateGraph(data)
+	_, count := dijkstra.GetShortestPath(data.From, data.To, graph)
+	return count
+}
+
+func inputGraph(maze Maze) dijkstra.InputGraph {
+	data := dijkstra.InputGraph{}
+	data.From = dijkstra.Point{X: maze.start.x, Y: maze.start.y}
+	data.To = dijkstra.Point{X: maze.end.x, Y: maze.end.y}
+	for y := 0; y < maze.height; y++ {
+		for x := 0; x < maze.width; x++ {
+			if maze.grid.Get(x, y) == WALL {
+				continue
+			}
+			for _, dir := range DIRECTIONS {
+				nx, ny := x+dir.x, y+dir.y
+				if nx < 0 || ny < 0 || nx >= maze.width || ny >= maze.height {
+					continue
+				}
+				if maze.grid.Get(nx, ny) == WALL {
+					continue
+				}
+				data.Graph = append(data.Graph, dijkstra.InputData{
+					Source:      dijkstra.Point{X: x, Y: y},
+					Destination: dijkstra.Point{X: nx, Y: ny},
+					Weight:      1,
+				})
+			}
+		}
+	}
+
+	return data
+}
+
+func (m Maze) Parse(input string, bytes int) *Maze {
+	m.grid = grid2d.NewGrid(71, 71, CORRIDOR)
+	for _, line := range strings.Split(input, "\n") {
+		if bytes == 0 {
+			break
+		}
+		in := strings.Split(line, ",")
+		x := utils.MustAtoi(in[0])
+		y := utils.MustAtoi(in[1])
+		m.grid.Set(x, y, WALL)
+		bytes--
+	}
+	m.start = Vec{0, 0}
+	m.end = Vec{70, 70}
+	m.height, m.width = m.grid.SizeY(), m.grid.SizeX()
+	return &m
+}
+
+func (m *Maze) String() string {
+	s := ""
+	for y := 0; y < m.height; y++ {
+		for x := 0; x < m.width; x++ {
+			if y == m.start.y && x == m.start.x {
+				s += string(START)
+			} else if y == m.end.y && x == m.end.x {
+				s += string(END)
+			} else {
+				s += string(m.grid.Get(x, y))
+			}
+		}
+		s += "\n"
+	}
+	return s
+}