advent-of-code-2022/day15/common/beacon.go

package common

import (
  "bufio"
  "fmt"
  "strconv"
  "strings"
)


type Tile byte

const (
  Sensor Tile = iota
  Beacon
  Covered
  Free
)


type Map struct {
  sensors []SensorPosition
  minX int
  maxX int
  minY int
  maxY int
}

func NewMap() *Map {
  tileMap := Map{}
  tileMap.sensors = []SensorPosition{}
  tileMap.minX = 0
  tileMap.maxX = 0
  tileMap.minY = 0
  tileMap.maxY = 0
  return &tileMap
}

func (tileMap *Map) GetTile(x, y int) Tile {
  for _, sensor := range tileMap.sensors {
    if sensor.x == x && sensor.y == y {
      return Sensor
    } else if sensor.xBeacon == x && sensor.yBeacon == y {
      return Beacon
    }
  }

  for _, sensor := range tileMap.sensors {
    coverageX := sensor.x - sensor.xBeacon
    if coverageX < 0 {
      coverageX *= -1
    }
    coverageY := sensor.y - sensor.yBeacon
    if coverageY < 0 {
      coverageY *= -1
    }
    coverage := coverageX + coverageY

    distanceX := sensor.x - x
    if distanceX < 0 {
      distanceX *= -1
    }
    distanceY := sensor.y - y
    if distanceY < 0 {
      distanceY *= -1
    }
    distance := distanceX + distanceY

    if distance <= coverage {
      return Covered
    }
  }

  return Free
}

func (tileMap *Map) SetSensor(sensor SensorPosition) {
  tileMap.sensors = append(tileMap.sensors, sensor)

  coverageX := sensor.x - sensor.xBeacon
  if coverageX < 0 {
    coverageX *= -1
  }
  coverageY := sensor.y - sensor.yBeacon
  if coverageY < 0 {
    coverageY *= -1
  }
  coverage := coverageX + coverageY

  if sensor.x - coverage < tileMap.minX {
    tileMap.minX = sensor.x - coverage
  }
  if sensor.x + coverage > tileMap.maxX {
    tileMap.maxX = sensor.x + coverage
  }
  if sensor.y - coverage < tileMap.minY {
    tileMap.minY = sensor.y - coverage
  }
  if sensor.y + coverage > tileMap.maxY {
    tileMap.maxY = sensor.y + coverage
  }
}

func (tileMap *Map) GetCoverageY(y int) int {
  return tileMap.GetCoverageYInXInterval(tileMap.minX, tileMap.maxX, y)
}

func (tileMap *Map) GetCoverageYInXInterval(xMin, xMax, y int) int {
  coverages := []struct{min int; max int}{}
  nCovered := 0
  foundBeacons := make(map[int]struct{})

  for _, sensor := range tileMap.sensors {
    if _, ok := foundBeacons[sensor.xBeacon]; !ok && sensor.yBeacon == y && sensor.xBeacon >= xMin && sensor.xBeacon <= xMax {
      foundBeacons[sensor.xBeacon] = struct{}{}
      nCovered--
    }

    coverageX := sensor.x - sensor.xBeacon
    if coverageX < 0 {
      coverageX *= -1
    }
    coverageY := sensor.y - sensor.yBeacon
    if coverageY < 0 {
      coverageY *= -1
    }
    coverage := coverageX + coverageY
    
    if y >= sensor.y - coverage && y <= sensor.y + coverage {
      distanceY := sensor.y - y
      if distanceY < 0 {
        distanceY *= -1
      }
      
      distanceX := coverage - distanceY
      coverageXMin := sensor.x - distanceX
      if coverageXMin < xMin {
        coverageXMin = xMin
      }
      coverageXMax := sensor.x + distanceX
      if coverageXMax > xMax {
        coverageXMax = xMax
      }
 
      coverages = append(coverages, struct{min int; max int}{coverageXMin, coverageXMax})
    }
  }

  for i := 0; i < len(coverages); i++ {
    for j := 0; j < len(coverages); j++ {
      if j != i {
        found := false
        if coverages[j].min >= coverages[i].min && coverages[j].min <= coverages[i].max && coverages[j].max >= coverages[i].max {
          coverages[i].max = coverages[j].max
          found = true
        } else if coverages[j].min <= coverages[i].min && coverages[j].max >= coverages[i].min && coverages[j].max <= coverages[i].max {
          coverages[i].min = coverages[j].min
          found = true
        } else if coverages[j].min < coverages[i].min && coverages[j].max > coverages[i].max {
          coverages[i].min = coverages[j].min
          coverages[i].max = coverages[j].max
          found = true
        } else if coverages[j].min >= coverages[i].min && coverages[j].max <= coverages[i].max {
          found = true
        }
        if found {
          if j == 0 {
            coverages = coverages[1:]
          } else if j == len(coverages) - 1 {
            coverages = coverages[:len(coverages)-1]
          } else {
            coverages = append(coverages[0:j], coverages[j+1:]...)
          }
          j = 0
        }
      }
    }
  }

  for _, coverage := range(coverages) {
    nCovered += coverage.max - coverage.min + 1
  }

  return nCovered
}

func (tileMap *Map) Print(xMin, xMax, yMin, yMax int) {
  for i := yMin; i <= yMax; i++ {
    for j := xMin; j <= xMax; j++ {
      switch tileMap.GetTile(j, i) {
        case Beacon:
          fmt.Print("B")
        case Sensor:
          fmt.Print("S")
        case Covered:
          fmt.Print("#")
        case Free:
          fmt.Print(".")
      }
    }
    fmt.Println()
  }
}


type SensorPosition struct {
  x int
  y int
  xBeacon int
  yBeacon int
}


func Parse(scanner bufio.Scanner) []SensorPosition {
  sensors := []SensorPosition{}

  for scanner.Scan() {
    line := scanner.Text()
    splittedLine := strings.Split(line, " ")
    x, _ := strconv.Atoi(splittedLine[2][2:len(splittedLine[2])-1])
    y, _ := strconv.Atoi(splittedLine[3][2:len(splittedLine[3])-1])
    xBeacon, _ := strconv.Atoi(splittedLine[8][2:len(splittedLine[8])-1])
    yBeacon, _ := strconv.Atoi(splittedLine[9][2:])

    sensors = append(sensors, SensorPosition{x, y, xBeacon, yBeacon})
  }

  return sensors
}