Created
March 27, 2022 22:10
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bfs/dfs implementation of a graph in Scala 3
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import scala.annotation.tailrec | |
class Graph[A](m: Map[A, Set[A]]): | |
type Vertex = A | |
type GraphMap = Map[Vertex, Set[Vertex]] | |
private def neighbors(v: Vertex): List[Vertex] = | |
m.get(v).map(_.toList).getOrElse(List.empty[Vertex]) | |
def search(start: Vertex, end: Vertex): Boolean = | |
@tailrec | |
def bfs(toVisit: List[Vertex], visited: List[Vertex]): Boolean = | |
toVisit.headOption match | |
case Some(current) if (current == end) => true | |
case Some(current) if visited.exists(_ == current) => bfs(toVisit.tail, visited) | |
case Some(current) => | |
val ns: List[Vertex] = neighbors(current) | |
val newToVisit: List[Vertex] = toVisit.tail ++ ns | |
bfs(newToVisit, current::visited) | |
case None => false | |
@tailrec | |
def dfs(toVisit: List[Vertex], visited: List[Vertex]): Boolean = | |
toVisit.headOption match | |
case Some(current) if (current == end) => true | |
case Some(current) if visited.exists(_ == current) => dfs(toVisit.tail, visited) | |
case Some(current) => | |
val ns: List[Vertex] = neighbors(current) | |
val newToVisit: List[Vertex] = ns ++ toVisit.tail | |
dfs(newToVisit, current::visited) | |
case None => false | |
bfs(List(start), List.empty[Vertex]) && | |
dfs(List(start), List.empty[Vertex]) | |
object Main: | |
def main(args: Array[String]): Unit = | |
val m = Map(("A" -> Set("B", "C")), | |
("B" -> Set("D", "E")), | |
("C" -> Set("F", "G")), | |
) | |
val path = Graph(m).search("A", "G") | |
println(path) |
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