Minimum steps to reach target by a Knight In Scala
0
Given a chessboard of N size (square matrix), the position of Knight and position of a target find out minimum steps ( both count and exact steps) from start tp target for a Knight.
If it is not possible to reach to the given position return -1 as step count.
Here is implementation in scala (assuming N = 4 or 4X4 chess board).
import scala.collection.mutable._
object KnightMoves extends App {
case class Pos(row: Int, col: Int)
val Size = 4
def calculateMoves(from: Pos, target: Pos ): (Int, Seq[Pos])= {
val pendingPos = collection.mutable.Queue[Pos](from)
val positionVisited = collection.mutable.HashMap[Pos, (Int, Seq[Pos])](from -> (0, Seq()))
var targetReached = false
while(pendingPos.nonEmpty && !targetReached) {
val p = pendingPos.dequeue()
possibleMoves(p) foreach { position =>
if ( position == target) {
targetReached = true
} else if (!(positionVisited contains position)) {
pendingPos enqueue position
}
positionVisited += position -> ((positionVisited(p)._1 + 1,(positionVisited(p)._2 ++ Seq(p))))
}
}
if (targetReached) positionVisited(target) else (-1, Seq())
}
def isValidPos(position: Pos): Boolean =
((0 until Size) contains position.row) && ((0 until Size) contains position.col)
def possibleMoves(position: Pos): List[Pos] =
List(Pos(position.row - 2, position.col + 1),
Pos(position.row - 2, position.col - 1),
Pos(position.row + 2, position.col + 1),
Pos(position.row + 2, position.col - 1),
Pos(position.row - 1 , position.col + 2),
Pos(position.row - 1 , position.col - 2),
Pos(position.row + 1 , position.col + 2),
Pos(position.row + 1 , position.col - 2)
) filter( pos => isValidPos(pos))
println(calculateMoves(Pos(0,1),Pos(0,0)))
println(calculateMoves(Pos(0,1),Pos(0,2)))
}
Program generate following output for two test statements at bottom.
(3,ArrayBuffer(Pos(0,1), Pos(2,0), Pos(1,2)))
(3,ArrayBuffer(Pos(0,1), Pos(2,2), Pos(1,0)))
interview-questions functional-programming matrix scala cache
asked 10 mins ago
vikrant
787
add a comment |
0
Given a chessboard of N size (square matrix), the position of Knight and position of a target find out minimum steps ( both count and exact steps) from start tp target for a Knight.
If it is not possible to reach to the given position return -1 as step count.
Here is implementation in scala (assuming N = 4 or 4X4 chess board).
import scala.collection.mutable._
object KnightMoves extends App {
case class Pos(row: Int, col: Int)
val Size = 4
def calculateMoves(from: Pos, target: Pos ): (Int, Seq[Pos])= {
val pendingPos = collection.mutable.Queue[Pos](from)
val positionVisited = collection.mutable.HashMap[Pos, (Int, Seq[Pos])](from -> (0, Seq()))
var targetReached = false
while(pendingPos.nonEmpty && !targetReached) {
val p = pendingPos.dequeue()
possibleMoves(p) foreach { position =>
if ( position == target) {
targetReached = true
} else if (!(positionVisited contains position)) {
pendingPos enqueue position
}
positionVisited += position -> ((positionVisited(p)._1 + 1,(positionVisited(p)._2 ++ Seq(p))))
}
}
if (targetReached) positionVisited(target) else (-1, Seq())
}
def isValidPos(position: Pos): Boolean =
((0 until Size) contains position.row) && ((0 until Size) contains position.col)
def possibleMoves(position: Pos): List[Pos] =
List(Pos(position.row - 2, position.col + 1),
Pos(position.row - 2, position.col - 1),
Pos(position.row + 2, position.col + 1),
Pos(position.row + 2, position.col - 1),
Pos(position.row - 1 , position.col + 2),
Pos(position.row - 1 , position.col - 2),
Pos(position.row + 1 , position.col + 2),
Pos(position.row + 1 , position.col - 2)
) filter( pos => isValidPos(pos))
println(calculateMoves(Pos(0,1),Pos(0,0)))
println(calculateMoves(Pos(0,1),Pos(0,2)))
}
Program generate following output for two test statements at bottom.
(3,ArrayBuffer(Pos(0,1), Pos(2,0), Pos(1,2)))
(3,ArrayBuffer(Pos(0,1), Pos(2,2), Pos(1,0)))
interview-questions functional-programming matrix scala cache
asked 10 mins ago
vikrant
787
add a comment |
0
0
0
Given a chessboard of N size (square matrix), the position of Knight and position of a target find out minimum steps ( both count and exact steps) from start tp target for a Knight.
If it is not possible to reach to the given position return -1 as step count.
Here is implementation in scala (assuming N = 4 or 4X4 chess board).
import scala.collection.mutable._
object KnightMoves extends App {
case class Pos(row: Int, col: Int)
val Size = 4
def calculateMoves(from: Pos, target: Pos ): (Int, Seq[Pos])= {
val pendingPos = collection.mutable.Queue[Pos](from)
val positionVisited = collection.mutable.HashMap[Pos, (Int, Seq[Pos])](from -> (0, Seq()))
var targetReached = false
while(pendingPos.nonEmpty && !targetReached) {
val p = pendingPos.dequeue()
possibleMoves(p) foreach { position =>
if ( position == target) {
targetReached = true
} else if (!(positionVisited contains position)) {
pendingPos enqueue position
}
positionVisited += position -> ((positionVisited(p)._1 + 1,(positionVisited(p)._2 ++ Seq(p))))
}
}
if (targetReached) positionVisited(target) else (-1, Seq())
}
def isValidPos(position: Pos): Boolean =
((0 until Size) contains position.row) && ((0 until Size) contains position.col)
def possibleMoves(position: Pos): List[Pos] =
List(Pos(position.row - 2, position.col + 1),
Pos(position.row - 2, position.col - 1),
Pos(position.row + 2, position.col + 1),
Pos(position.row + 2, position.col - 1),
Pos(position.row - 1 , position.col + 2),
Pos(position.row - 1 , position.col - 2),
Pos(position.row + 1 , position.col + 2),
Pos(position.row + 1 , position.col - 2)
) filter( pos => isValidPos(pos))
println(calculateMoves(Pos(0,1),Pos(0,0)))
println(calculateMoves(Pos(0,1),Pos(0,2)))
}
Program generate following output for two test statements at bottom.
(3,ArrayBuffer(Pos(0,1), Pos(2,0), Pos(1,2)))
(3,ArrayBuffer(Pos(0,1), Pos(2,2), Pos(1,0)))
interview-questions functional-programming matrix scala cache
asked 10 mins ago
vikrant
787
Given a chessboard of N size (square matrix), the position of Knight and position of a target find out minimum steps ( both count and exact steps) from start tp target for a Knight.
If it is not possible to reach to the given position return -1 as step count.
Here is implementation in scala (assuming N = 4 or 4X4 chess board).
import scala.collection.mutable._
object KnightMoves extends App {
case class Pos(row: Int, col: Int)
val Size = 4
def calculateMoves(from: Pos, target: Pos ): (Int, Seq[Pos])= {
val pendingPos = collection.mutable.Queue[Pos](from)
val positionVisited = collection.mutable.HashMap[Pos, (Int, Seq[Pos])](from -> (0, Seq()))
var targetReached = false
while(pendingPos.nonEmpty && !targetReached) {
val p = pendingPos.dequeue()
possibleMoves(p) foreach { position =>
if ( position == target) {
targetReached = true
} else if (!(positionVisited contains position)) {
pendingPos enqueue position
}
positionVisited += position -> ((positionVisited(p)._1 + 1,(positionVisited(p)._2 ++ Seq(p))))
}
}
if (targetReached) positionVisited(target) else (-1, Seq())
}
def isValidPos(position: Pos): Boolean =
((0 until Size) contains position.row) && ((0 until Size) contains position.col)
def possibleMoves(position: Pos): List[Pos] =
List(Pos(position.row - 2, position.col + 1),
Pos(position.row - 2, position.col - 1),
Pos(position.row + 2, position.col + 1),
Pos(position.row + 2, position.col - 1),
Pos(position.row - 1 , position.col + 2),
Pos(position.row - 1 , position.col - 2),
Pos(position.row + 1 , position.col + 2),
Pos(position.row + 1 , position.col - 2)
) filter( pos => isValidPos(pos))
println(calculateMoves(Pos(0,1),Pos(0,0)))
println(calculateMoves(Pos(0,1),Pos(0,2)))
}
Program generate following output for two test statements at bottom.
(3,ArrayBuffer(Pos(0,1), Pos(2,0), Pos(1,2)))
(3,ArrayBuffer(Pos(0,1), Pos(2,2), Pos(1,0)))
interview-questions functional-programming matrix scala cache
interview-questions functional-programming matrix scala cache
asked 10 mins ago
vikrant
787
asked 10 mins ago
vikrant
787
asked 10 mins ago
vikrant
787
asked 10 mins ago
vikrant
787
asked 10 mins ago
vikrant
787
787
add a comment |
add a comment |
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