Day 22

day22/common/forcefield.go

@@ -0,0 +1,333 @@
+package common
+
+import (
+	"bufio"
+	"strconv"
+)
+
+
+type Tile byte
+
+const (
+  None Tile = iota
+  Empty
+  Wall
+)
+
+
+type Direction byte
+
+const (
+  East Direction = iota
+  West
+  North
+  South
+)
+
+
+type Traveler struct {
+  facing Direction
+  x int
+  y int
+}
+
+
+type Map struct {
+  tiles [][]Tile
+  traveler Traveler
+  isCubic bool
+}
+
+func (tileMap *Map) GetNextTile() (int, int, Direction) {
+  nextX := tileMap.traveler.x
+  nextY := tileMap.traveler.y
+  nextDirection := tileMap.traveler.facing
+  
+  switch nextDirection {
+    case East:
+      if nextX + 1 < len(tileMap.tiles[nextY]) && tileMap.tiles[nextY][nextX+1] == Empty {
+        nextX++
+      } else if nextX + 1 == len(tileMap.tiles[nextY]) || tileMap.tiles[nextY][nextX+1] == None {
+        if tileMap.isCubic {
+          if nextX == 149 {
+            if tileMap.tiles[149-nextY][99] == Empty {
+              nextX = 99
+              nextY = 149 - nextY
+              nextDirection = West
+            }
+          } else if nextX == 99 && nextY < 100 {
+            if tileMap.tiles[49][nextY+50] == Empty {
+              nextX = nextY + 50
+              nextY = 49
+              nextDirection = North
+            }
+          } else if nextX == 99 {
+            if tileMap.tiles[149-nextY][149] == Empty {
+              nextX = 149
+              nextY = 149 - nextY
+              nextDirection = West
+            }
+          } else {
+            if tileMap.tiles[149][nextY-100] == Empty {
+              nextX = nextY - 100
+              nextY = 149
+              nextDirection = North
+            }
+          }
+        } else {
+          for i := 0; i < len(tileMap.tiles[nextY]); i++ {
+            if tileMap.tiles[nextY][i] != None {
+              if tileMap.tiles[nextY][i] == Empty {
+                nextX = i
+              }
+              break
+            }
+          }
+        }
+      }
+
+    case West:
+      if nextX - 1 >= 0 && tileMap.tiles[nextY][nextX-1] == Empty {
+        nextX--
+      } else if nextX - 1 < 0 || tileMap.tiles[nextY][nextX-1] == None {
+        if tileMap.isCubic {
+          if nextX == 50 && nextY < 50 {
+            if tileMap.tiles[149-nextY][0] == Empty {
+              nextX = 0
+              nextY = 149 - nextY
+              nextDirection = East
+            }
+          } else if nextX == 50 {
+            if tileMap.tiles[100][nextY-50] == Empty {
+              nextX = nextY - 50
+              nextY = 100
+              nextDirection = South
+            }
+          } else if nextY < 150 {
+            if tileMap.tiles[149-nextY][50] == Empty {
+              nextX = 50
+              nextY = 149 - nextY
+              nextDirection = East
+            }
+          } else {
+            if tileMap.tiles[0][nextY-100] == Empty {
+              nextX = nextY - 100
+              nextY = 0
+              nextDirection = South
+            }
+          }
+        } else {
+          for i := len(tileMap.tiles[nextY]) - 1; i >= 0; i-- {
+            if tileMap.tiles[nextY][i] != None {
+              if tileMap.tiles[nextY][i] == Empty {
+                nextX = i
+              }
+              break
+            }
+          }
+        }
+      }
+
+    case North:
+      if nextY - 1 >= 0 && tileMap.tiles[nextY-1][nextX] == Empty {
+        nextY--
+      } else if nextY - 1 < 0 || tileMap.tiles[nextY-1][nextX] == None {
+        if tileMap.isCubic {
+          if nextX < 50 {
+            if tileMap.tiles[nextX+50][50] == Empty {
+              nextY = nextX + 50
+              nextX = 50
+              nextDirection = East
+            }
+          } else if nextX < 100 {
+            if tileMap.tiles[nextX+100][0] == Empty {
+              nextY = nextX + 100
+              nextX = 0
+              nextDirection = East
+            }
+          } else {
+            if tileMap.tiles[199][nextX-100] == Empty {
+              nextX = nextX - 100
+              nextY = 199
+            }
+          }
+        } else {
+          for i := len(tileMap.tiles) - 1; i >= 0; i-- {
+            if tileMap.tiles[i][nextX] != None {
+              if tileMap.tiles[i][nextX] == Empty {
+                nextY = i
+              }
+              break
+            }
+          }
+        }
+      }
+
+    case South:
+      if nextY + 1 < len(tileMap.tiles) && tileMap.tiles[nextY+1][nextX] == Empty {
+        nextY++
+      } else if nextY + 1 == len(tileMap.tiles) || tileMap.tiles[nextY+1][nextX] == None {
+        if tileMap.isCubic {
+          if nextX < 50 {
+            if tileMap.tiles[0][nextX+100] == Empty {
+              nextX = nextX + 100
+              nextY = 0
+            }
+          } else if nextX < 100 {
+            if tileMap.tiles[nextX+100][49] == Empty {
+              nextY = nextX + 100
+              nextX = 49
+              nextDirection = West
+            }
+          } else {
+            if tileMap.tiles[nextX-50][99] == Empty {
+              nextY = nextX - 50
+              nextX = 99
+              nextDirection = West
+            }
+          }
+        } else {
+          for i := 0; i < len(tileMap.tiles); i++ {
+            if tileMap.tiles[i][nextX] != None {
+              if tileMap.tiles[i][nextX] == Empty {
+                nextY = i
+              }
+              break
+            }
+          }
+        }
+      }
+  }
+
+  return nextX, nextY, nextDirection
+}
+
+func (tileMap *Map) GetPassword() int {
+  password := 1000 * (tileMap.traveler.y + 1) + 4 * (tileMap.traveler.x + 1)
+  switch tileMap.traveler.facing {
+    case South:
+      password += 1
+    case West:
+      password += 2
+    case North:
+      password += 3
+  }
+
+  return password
+}
+
+
+type Instruction interface {
+  Apply(*Map)
+}
+
+
+type Move struct {
+  nTiles int
+}
+
+func (instruction Move) Apply(tileMap *Map) {
+  for i := 0; i < instruction.nTiles; i++ {
+    nextX, nextY, nextDirection := tileMap.GetNextTile()
+    tileMap.traveler.x = nextX
+    tileMap.traveler.y = nextY
+    tileMap.traveler.facing = nextDirection
+  }
+}
+
+
+type RotateClockwise struct {}
+
+func (instruction RotateClockwise) Apply(tileMap *Map) {
+  switch tileMap.traveler.facing {
+    case East:
+      tileMap.traveler.facing = South
+    case South:
+      tileMap.traveler.facing = West
+    case West:
+      tileMap.traveler.facing = North
+    case North:
+      tileMap.traveler.facing = East
+  }
+}
+
+
+type RotateCounterclockwise struct {}
+
+func (instruction RotateCounterclockwise) Apply(tileMap *Map) {
+  switch tileMap.traveler.facing {
+    case East:
+      tileMap.traveler.facing = North
+    case South:
+      tileMap.traveler.facing = East
+    case West:
+      tileMap.traveler.facing = South
+    case North:
+      tileMap.traveler.facing = West
+  }
+}
+
+
+func Parse(scanner bufio.Scanner, isCubic bool) (Map, []Instruction) {
+  tileMap := Map{}
+  instructions := []Instruction{}
+  longestRow := 0
+
+  for scanner.Scan() {
+    line := scanner.Text()
+
+    if line == "" {
+      scanner.Scan()
+      line := scanner.Text()
+      for i := 0; i < len(line); i++ {
+        if line[i] >= '0' && line[i] <= '9' {
+          j := i
+          for j < len(line) && line[j] >= '0' && line[j] <= '9' {
+            j++
+          }
+          nTiles, _ := strconv.Atoi(line[i:j])
+          instructions = append(instructions, Move{nTiles})
+          i = j - 1
+        } else if line[i] == 'L' {
+          instructions = append(instructions, RotateCounterclockwise{})
+        } else if line[i] == 'R' {
+          instructions = append(instructions, RotateClockwise{})
+        }
+      }
+    } else {
+      if len(line) > longestRow {
+        longestRow = len(line)
+      }
+
+      tileRow := make([]Tile, len(line))
+      for i := range line {
+        switch line[i] {
+          case ' ':
+            tileRow[i] = None
+          case '.':
+            tileRow[i] = Empty
+          case '#':
+            tileRow[i] = Wall
+        }
+      }
+      tileMap.tiles = append(tileMap.tiles, tileRow)
+    }
+  }
+  
+  for i := range tileMap.tiles {
+    for len(tileMap.tiles[i]) < longestRow {
+      tileMap.tiles[i] = append(tileMap.tiles[i], None)
+    }
+  }
+
+  for i := range tileMap.tiles[0] {
+    if tileMap.tiles[0][i] == Empty {
+      tileMap.traveler = Traveler{East, i, 0}
+      break
+    }
+  }
+
+  tileMap.isCubic = isCubic
+
+  return tileMap, instructions
+}