Add transit node routing comment

Author: sim642

src/main/scala/eu/sim642/adventofcode2019/Day18.scala

@@ -23,6 +23,7 @@ object Day18 {
   trait KeyNeighborsSolution extends Solution {
     case class PathData(distance: Int, pathDoors: Set[Pos], pathKeys: Set[Pos])
 
+    // https://en.wikipedia.org/wiki/Transit_node_routing
     def getKeyNeighbors(input: Input): collection.Map[Pos, collection.Map[Pos, PathData]]
 
     override def collectKeysSteps(input: Input): Int = {

src/main/scala/eu/sim642/adventofcode2021/Day23.scala

@@ -33,6 +33,7 @@ object Day23 {
 
     private case class PathData(length: Int, pathPoss: Set[Pos])
 
+    // https://en.wikipedia.org/wiki/Transit_node_routing
     private val posNeighbors: collection.Map[Pos, collection.Map[Pos, PathData]] = {
       val allPoss: Set[Pos] = hallways ++ room2amphipod.keySet
 

src/main/scala/eu/sim642/adventofcode2022/Day16.scala

@@ -12,6 +12,7 @@ object Day16 {
 
   case class ValveData(flowRate: Int, tunnels: Seq[Valve])
 
+  // https://en.wikipedia.org/wiki/Transit_node_routing
   def valveDists(valves: Map[Valve, ValveData]): collection.Map[Valve, collection.Map[Valve, Int]] = {
     val dists: mutable.Map[Valve, mutable.Map[Valve, Int]] = valves.view.mapValues(_.tunnels.map(_ -> 1).to(mutable.Map)).to(mutable.Map)
     // Floyd-Warshall