Day 15. part 2.

day_15/solution.go

@@ -1,6 +1,8 @@
 package day_15
 
 import (
+	"fmt"
+	"slices"
 	"strings"
 )
 
@@ -9,7 +11,10 @@ const (
 	Player   = '@'
 	Box      = 'O'
 	Empty    = '.'
+	WideBoxL = '['
+	WideBoxR = ']'
 )
+
 const (
 	InstUp    = '^'
 	InstDown  = 'v'
@@ -19,6 +24,12 @@ const (
 
 type Warehouse [][]rune
 
+func (w Warehouse) Print() {
+	for _, line := range w {
+		fmt.Println(string(line))
+	}
+}
+
 func (w Warehouse) At(x, y int) rune {
 	if x < 0 || y < 0 || x >= len(w[0]) || y >= len(w) {
 		return Wall
@@ -57,7 +68,31 @@ func SolveBasic(input string) int {
 
 // task:https://adventofcode.com/2024/day/12#part2
 func SolveComplex(input string) int {
-	return 0
+	warehouse, instructions, rX, rY := loadWide(input)
+
+	for _, instr := range instructions {
+		switch instr {
+		case InstUp:
+			rX, rY = moveWideUp(warehouse, rX, rY)
+		case InstDown:
+			rX, rY = moveWideDown(warehouse, rX, rY)
+		case InstLeft:
+			rX, rY = moveWideLeft(warehouse, rX, rY)
+		case InstRight:
+			rX, rY = moveWideRight(warehouse, rX, rY)
+		default:
+			panic("unknown instruction " + string(instr))
+		}
+	}
+	sum := 0
+	for y, line := range warehouse {
+		for x, val := range line {
+			if val == WideBoxL {
+				sum += y*100 + x
+			}
+		}
+	}
+	return sum
 }
 
 func load(input string) (Warehouse, []rune, int, int) {
@@ -77,6 +112,32 @@ func load(input string) (Warehouse, []rune, int, int) {
 	return warehouse, instructions, rX, rY
 }
 
+func loadWide(input string) (Warehouse, []rune, int, int) {
+	substrings := strings.Split(input, "\n\n")
+	warehouse := Warehouse{}
+	rX := 0
+	rY := 0
+	for y, line := range strings.Split(substrings[0], "\n") {
+		line = expandLine(line)
+		if strings.ContainsRune(line, Player) {
+			rY = y
+			rX = strings.IndexRune(line, Player)
+		}
+		warehouse = append(warehouse, []rune(line))
+	}
+	instructions := []rune(strings.ReplaceAll(substrings[1], "\n", ""))
+
+	return warehouse, instructions, rX, rY
+}
+
+func expandLine(line string) string {
+	line = strings.ReplaceAll(line, "#", "##")
+	line = strings.ReplaceAll(line, ".", "..")
+	line = strings.ReplaceAll(line, "@", "@.")
+	line = strings.ReplaceAll(line, "O", "[]")
+	return line
+}
+
 func moveUp(warehouse Warehouse, x int, y int) (int, int) {
 	if warehouse.At(x, y-1) == Wall {
 		return x, y
@@ -160,3 +221,139 @@ func moveRight(warehouse Warehouse, x int, y int) (int, int) {
 	}
 	return x, y
 }
+
+func moveWideUp(warehouse Warehouse, x int, y int) (int, int) {
+	if warehouse.At(x, y-1) == Wall {
+		return x, y
+	} else if warehouse.At(x, y-1) == Empty {
+		warehouse[y][x] = Empty
+		warehouse[y-1][x] = Player
+		return x, y - 1
+	} else {
+		type Point struct {
+			x, y int
+		}
+		checkable := []Point{{x, y}}
+
+		for i := 0; i < len(checkable); i++ {
+			p := checkable[i]
+			l := warehouse.At(p.x, p.y-1)
+			if l == Wall {
+				return x, y
+			}
+			if l == WideBoxL {
+				if !slices.Contains(checkable, Point{p.x, p.y - 1}) {
+					checkable = append(checkable, Point{p.x, p.y - 1})
+				}
+				if !slices.Contains(checkable, Point{p.x + 1, p.y - 1}) {
+					checkable = append(checkable, Point{p.x + 1, p.y - 1})
+				}
+			}
+			if l == WideBoxR {
+				if !slices.Contains(checkable, Point{p.x, p.y - 1}) {
+					checkable = append(checkable, Point{p.x, p.y - 1})
+				}
+				if !slices.Contains(checkable, Point{p.x - 1, p.y - 1}) {
+					checkable = append(checkable, Point{p.x - 1, p.y - 1})
+				}
+			}
+		}
+		for i := len(checkable) - 1; i >= 0; i-- {
+			p := checkable[i]
+			warehouse[p.y-1][p.x] = warehouse[p.y][p.x]
+			warehouse[p.y][p.x] = Empty
+		}
+		return x, y - 1
+	}
+}
+
+func moveWideDown(warehouse Warehouse, x int, y int) (int, int) {
+	if warehouse.At(x, y+1) == Wall {
+		return x, y
+	} else if warehouse.At(x, y+1) == Empty {
+		warehouse[y][x] = Empty
+		warehouse[y+1][x] = Player
+		return x, y + 1
+	} else {
+		type Point struct {
+			x, y int
+		}
+		checkable := []Point{{x, y}}
+
+		for i := 0; i < len(checkable); i++ {
+			p := checkable[i]
+			l := warehouse.At(p.x, p.y+1)
+			if l == Wall {
+				return x, y
+			}
+			if l == WideBoxL {
+				if !slices.Contains(checkable, Point{p.x, p.y + 1}) {
+					checkable = append(checkable, Point{p.x, p.y + 1})
+				}
+				if !slices.Contains(checkable, Point{p.x + 1, p.y + 1}) {
+					checkable = append(checkable, Point{p.x + 1, p.y + 1})
+				}
+			}
+			if l == WideBoxR {
+				if !slices.Contains(checkable, Point{p.x, p.y + 1}) {
+					checkable = append(checkable, Point{p.x, p.y + 1})
+				}
+				if !slices.Contains(checkable, Point{p.x - 1, p.y + 1}) {
+					checkable = append(checkable, Point{p.x - 1, p.y + 1})
+				}
+			}
+		}
+		for i := len(checkable) - 1; i >= 0; i-- {
+			p := checkable[i]
+			warehouse[p.y+1][p.x] = warehouse[p.y][p.x]
+			warehouse[p.y][p.x] = Empty
+		}
+		return x, y + 1
+	}
+}
+
+func moveWideLeft(warehouse Warehouse, x int, y int) (int, int) {
+	if warehouse.At(x-1, y) == Wall {
+		return x, y
+	} else if warehouse.At(x-1, y) == Empty {
+		warehouse[y][x] = Empty
+		warehouse[y][x-1] = Player
+		return x - 1, y
+	} else {
+		newX := x - 1
+		for ; warehouse.At(newX, y) == WideBoxL || warehouse.At(newX, y) == WideBoxR; newX-- {
+		}
+		if warehouse.At(newX, y) == Empty {
+			for tx := newX; tx < x-1; tx++ {
+				warehouse[y][tx] = warehouse[y][tx+1]
+			}
+			warehouse[y][x-1] = Player
+			warehouse[y][x] = Empty
+			return x - 1, y
+		}
+	}
+	return x, y
+}
+
+func moveWideRight(warehouse Warehouse, x int, y int) (int, int) {
+	if warehouse.At(x+1, y) == Wall {
+		return x, y
+	} else if warehouse.At(x+1, y) == Empty {
+		warehouse[y][x] = Empty
+		warehouse[y][x+1] = Player
+		return x + 1, y
+	} else {
+		newX := x + 1
+		for ; warehouse.At(newX, y) == WideBoxL || warehouse.At(newX, y) == WideBoxR; newX++ {
+		}
+		if warehouse.At(newX, y) == Empty {
+			for tx := newX; tx > x+1; tx-- {
+				warehouse[y][tx] = warehouse[y][tx-1]
+			}
+			warehouse[y][x+1] = Player
+			warehouse[y][x] = Empty
+			return x + 1, y
+		}
+	}
+	return x, y
+}

day_15/solution_test.go

@@ -22,5 +22,5 @@ func TestBasicSolutionExample01(t *testing.T) {
 }
 
 func TestComplexSolutionExample(t *testing.T) {
-	helpers.Check(t, day_15.SolveComplex, helpers.Format(ExampleData), 0)
+	helpers.Check(t, day_15.SolveComplex, helpers.Format(ExampleData01), 9021)
 }