2024.15 - Part 2 WIP

Author: jerodev

.vscode/launch.json

@@ -0,0 +1,19 @@
+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": [
+
+        {
+            "name": "Launch Package",
+            "type": "go",
+            "request": "launch",
+            "mode": "auto",
+            "program": "${fileDirname}",
+            "args": [
+                "example.txt"
+            ]
+        }
+    ]
+}

2024/15-warehouse/example2.txt

@@ -0,0 +1,10 @@
+#########
+#....##.#
+#.......#
+#.@OO...#
+#.......#
+#...O...#
+#.......#
+#########
+
+>>vvvv>>^^^^

2024/15-warehouse/main.go

@@ -3,18 +3,20 @@ package main
 import (
 	"advent-of-code/util"
 	"bufio"
-	"bytes"
 	"fmt"
 )
 
 const (
-	boundry = '#'
-	box     = 'O'
-	empty   = '.'
-	up      = '^'
-	right   = '>'
-	down    = 'v'
-	left    = '<'
+	boundry  = '#'
+	box      = 'O'
+	boxLeft  = '['
+	boxRight = ']'
+	empty    = '.'
+
+	up    = '^'
+	right = '>'
+	down  = 'v'
+	left  = '<'
 )
 
 var moves = map[byte]position{
@@ -24,51 +26,77 @@ var moves = map[byte]position{
 	left:  {-1, 0},
 }
 
-var grid [][]byte
-var robot position
+var grid, grid2 [][]byte
+var robot, robot2 position
 
 func main() {
 	file := util.FileFromArgs()
 	scan := bufio.NewScanner(file)
 
 	// Read grid
-	var x int
 	for scan.Scan() {
 		row := scan.Bytes()
 		if len(row) == 0 {
 			break
 		}
 
-		x = bytes.IndexRune(row, '@')
-		if x > -1 {
-			robot.X = x
-			robot.Y = len(grid)
-		}
-
-		// Prevent scanner memory override
+		// Part 1: Prevent scanner memory override
 		gridRow := make([]byte, len(row))
 		copy(gridRow, row)
 		grid = append(grid, gridRow)
+
+		// Part 2
+		gridRow = make([]byte, 0, len(row)*2)
+		for x, b := range row {
+			switch b {
+			case '@':
+				robot.X = x
+				robot.Y = len(grid) - 1
+				robot2.X = 2 * x
+				robot2.Y = len(grid2)
+				gridRow = append(gridRow, '@', empty)
+			case boundry:
+				gridRow = append(gridRow, boundry, boundry)
+			case box:
+				gridRow = append(gridRow, boxLeft, boxRight)
+			case empty:
+				gridRow = append(gridRow, empty, empty)
+			}
+		}
+		grid2 = append(grid2, gridRow)
 	}
 
+	util.PrintMatrix(grid2)
+
 	// Move stuf arround
 	for scan.Scan() {
 		for _, b := range scan.Bytes() {
 			moveObject(robot.X, robot.Y, b, true)
+			moveObject2(robot2.X, robot2.Y, b, true)
+
+			// util.PrintMatrix(grid2)
 		}
 	}
 
 	// Find boxes in our grid
-	var result int
+	var result, result2 int
 	for y := range grid {
 		for x := range grid[y] {
 			if grid[y][x] == box {
 				result += 100*y + x
 			}
 		}
 	}
+	for y := range grid2 {
+		for x := range grid2[y] {
+			if grid2[y][x] == boxLeft {
+				result2 += 100*y + x
+			}
+		}
+	}
 
 	fmt.Println(result)
+	fmt.Println(result2)
 }
 
 type position struct {
@@ -98,3 +126,99 @@ func moveObject(x, y int, direction byte, isRobot bool) bool {
 
 	return true
 }
+
+func moveObject2(x, y int, direction byte, isRobot bool) bool {
+	dx := x + moves[direction].X
+	dy := y + moves[direction].Y
+
+	if grid2[dy][dx] == boundry {
+		return false
+	}
+
+	// Always start from the left box part
+	bx := dx
+	if grid2[dy][dx] == boxRight {
+		bx -= 1
+	}
+
+	if grid2[dy][bx] == boxLeft {
+		switch direction {
+		case up:
+			if (grid2[dy-1][bx] == empty && grid2[dy-1][bx+1] == empty) || (grid2[dy-1][bx] == boxRight && grid2[dy-1][bx+1] == boxLeft && can2BoxesMove(bx-1, y-1, direction) && moveObject2(bx, dy, direction, false) && moveObject2(bx+1, dy, direction, false)) || (grid2[dy-1][bx] == boxRight && grid2[dy-1][bx+1] == empty && moveObject2(bx, dy, direction, false)) || (grid2[dy-1][bx+1] == left && grid2[dy-1][bx] == empty && moveObject2(bx, dy, direction, false)) {
+				grid2[dy][bx] = empty
+				grid2[dy][bx+1] = empty
+				grid2[dy-1][bx] = boxLeft
+				grid2[dy-1][bx+1] = boxRight
+			} else {
+				return false
+			}
+		case right:
+			if grid2[dy][bx+2] == empty || (grid2[dy][bx+2] == boxLeft && moveObject2(bx+1, dy, direction, false)) {
+				grid2[dy][bx] = empty
+				grid2[dy][bx+1] = boxLeft
+				grid2[dy][bx+2] = boxRight
+			} else {
+				return false
+			}
+		case down:
+			if (grid2[dy+1][bx] == empty && grid2[dy+1][bx+1] == empty) || (grid2[dy+1][bx] == boxLeft && moveObject2(bx, dy, direction, false)) || (grid2[dy+1][bx] == boxRight && grid2[dy+1][bx+1] == boxLeft && can2BoxesMove(bx-2, dy+1, direction) && moveObject2(bx, dy, direction, false) && moveObject2(bx+1, dy, direction, false)) || (grid2[dy+1][bx] == boxRight && moveObject2(bx, dy, direction, false) && grid2[dy+1][bx+1] == empty) {
+				grid2[dy][bx] = empty
+				grid2[dy][bx+1] = empty
+				grid2[dy+1][bx] = boxLeft
+				grid2[dy+1][bx+1] = boxRight
+			} else {
+				return false
+			}
+		case left:
+			if grid2[dy][bx-1] == empty || (grid2[dy][bx-1] == boxRight && moveObject2(bx-1, dy, direction, false)) {
+				grid2[dy][bx+1] = empty
+				grid2[dy][bx] = boxRight
+				grid2[dy][bx-1] = boxLeft
+			} else {
+				return false
+			}
+		}
+	}
+
+	// All is well, move the object
+	if isRobot {
+		grid2[dy][dx] = grid2[y][x]
+		grid2[y][x] = empty
+
+		robot2.X = dx
+		robot2.Y = dy
+	}
+
+	return true
+}
+
+func can2BoxesMove(x, y int, direction byte) bool {
+	if direction == down {
+		y += 2
+	} else {
+		y -= 2
+	}
+
+	if y < 0 || y > len(grid)-1 || x > len(grid2[y])-4 {
+		return true
+	}
+
+	// Obstacles in the way?
+	for i := 0; i < 4; i++ {
+		if grid2[y][x+i] == boundry {
+			return false
+		}
+
+	}
+
+	// One+ box blocking?
+	if x > len(grid2[y])-5 {
+		for i := -1; i < 5; i++ {
+			if grid[y][x+i] == boxLeft && grid[y][x+i+1] == boxRight && !moveObject2(x+i, y, direction, false) {
+				return false
+			}
+		}
+	}
+
+	return true
+}