Merge pull request #38 from sweeneycai/sweeneycai

Sweeneycai

scala-leetcode/README.md

@@ -9,3 +9,5 @@ Leetcode Scala 实现
 ## author
 
 [dreamylost](./src/main/scala/io/github/dreamylost/dreamylost.md)
+
+[sweeneycai](./src/main/scala/io/github/sweeneycai/sweeneycai.md)
\ No newline at end of file

scala-leetcode/src/main/scala/io/github/sweeneycai/Leetcode_365.scala

+package io.github.sweeneycai
+
+/**
+  * 365. 水壶问题
+  */
+object WaterPouringProblem extends App {
+  def canMeasureWater(x: Int, y: Int, z: Int): Boolean = {
+    val game = new Pouring(Vector(x, y))
+    game.solutions(z).take(1).nonEmpty
+  }
+
+  class Pouring(capacity: Vector[Int]) {
+    // States
+    type State = Vector[Int]
+    val initialState: Vector[Int] = capacity map (x => 0)
+
+    // Moves
+    trait Move {
+      def change(state: State): State
+    }
+
+    case class Empty(glass: Int) extends Move {
+      def change(state: State): State = state updated (glass, 0)
+    }
+
+    case class Fill(glass: Int) extends Move {
+      def change(state: State): State = state updated (glass, capacity(glass))
+    }
+
+    case class Pour(from: Int, to: Int) extends Move {
+      def change(state: State): State = {
+        val amount = state(from) min (capacity(to) - state(to))
+        state updated (from, state(from) - amount) updated (to, state(to) + amount)
+      }
+    }
+
+    val glasses: Range = capacity.indices
+
+    val moves: Seq[Move] =
+      (for (g <- glasses) yield Empty(g)) ++
+        (for (g <- glasses) yield Fill(g)) ++
+        (for (from <- glasses; to <- glasses if from != to) yield Pour(from, to))
+
+    class Path(history: List[Move], val endState: State) {
+      //    def endState: State = (history foldRight initialState) (_ change _)
+
+      //    def endState: State = (history foldRight initialState)((move, state) => move.change(state))
+      //    private def trackState(xs: List[Move]): State = xs match {
+      //      case Nil => initialState
+      //      case move :: xs1 => move change trackState(xs1)
+      //    }
+      def extend(move: Move): Path = new Path(move :: history, move change endState)
+
+      override def toString: String = (history.reverse mkString " ") + "-->" + endState
+    }
+
+    val initialPath = new Path(Nil, initialState)
+
+    def from(paths: Set[Path], explored: Set[State]): Stream[Set[Path]] =
+      if (paths.isEmpty) Stream.empty
+      else {
+        val more = for {
+          path <- paths
+          next <- moves map path.extend
+          if !(explored contains next.endState)
+        } yield next
+        paths #:: from(more, explored ++ (more map (_.endState)))
+      }
+
+    val pathSets = from(Set(initialPath), Set(initialState))
+
+    def solutions(target: Int): Stream[Path] =
+      for {
+        pathSet <- pathSets
+        path <- pathSet
+        if (path.endState contains target) || path.endState.sum == target
+      } yield path
+  }
+
+  val pouring = new Pouring(Vector(3, 5))
+  println(pouring.solutions(4).take(1))
+}

scala-leetcode/src/main/scala/io/github/sweeneycai/sweeneycai.md

+### 其他
+
+- [水壶问题](https://leetcode-cn.com/problems/water-and-jug-problem/)