update

Author: yangbajing

algs4-scala/src/main/scala/org/gs/digraph/AcyclicSP.scala

@@ -19,7 +19,7 @@ class AcyclicSP(g: EdgeWeightedDigraph, s: Int) {
   private val edgeTo = Array.fill[Option[DirectedEdge]](g.numV)(None)
   private val topological = new Topological(g)
 
-  topological.order match {
+  topological.order() match {
     case None => throw new IllegalArgumentException(s"EdgeWeightedDigraph:$g is not acyclic")
     case Some(x) =>
       for {
@@ -29,8 +29,8 @@ class AcyclicSP(g: EdgeWeightedDigraph, s: Int) {
   }
 
   private def relax(e: DirectedEdge): Unit = {
-    val v = e.from
-    val w = e.to
+    val v = e.from()
+    val w = e.to()
     if (_distTo(w) > _distTo(v) + e.weight) {
       _distTo(w) = _distTo(v) + e.weight
       edgeTo(w) = Some(e)
@@ -49,10 +49,9 @@ class AcyclicSP(g: EdgeWeightedDigraph, s: Int) {
     else {
       val path = new ListBuffer[DirectedEdge]()
 
-      @tailrec
-      def loop(e: DirectedEdge) {
+      @tailrec def loop(e: DirectedEdge) {
         e +=: path
-        edgeTo(e.from) match {
+        edgeTo(e.from()) match {
           case None    =>
           case Some(x) => loop(x)
         }

algs4-scala/src/main/scala/org/gs/digraph/EdgeWeightedDepthFirstOrder.scala

@@ -1,7 +1,5 @@
 package org.gs.digraph
 
-import scala.collection.mutable.Queue
-
 /** Depth first order for an EdgeWeightedDigraph
  *
  * @constructor creates a new EdgeWeightedDepthFirstOrder with an EdgeWeightedDigraph, vertex count
@@ -15,7 +13,7 @@ class EdgeWeightedDepthFirstOrder(g: EdgeWeightedDigraph) extends BaseDepthFirst
     preCounter += 1
     _pre(v) = preCounter
     preOrder.enqueue(v)
-    g.adj(v) foreach (e => if (!marked(e.to)) dfs(e.to))
+    g.adj(v) foreach (e => if (!marked(e.to())) dfs(e.to()))
     postOrder.enqueue(v)
     postCounter += 1
     _post(v) = postCounter

algs4-scala/src/main/scala/org/gs/digraph/IndexedSeq.scala

@@ -0,0 +1,25 @@
+package org.gs.digraph
+
+import scala.annotation.tailrec
+
+class IndexedSeq[+A] extends scala.collection.IndexedSeq[A] {
+  override def apply(i: Int): A = ???
+
+  override def length: Int = ???
+
+  override def foldLeft[B](z: B)(op: (B, A) => B): B = {
+    @inline @tailrec def inner(acc: B, n: Int): B =
+      if (n == length) acc
+      else inner(op(acc, apply(n)), n + 1)
+
+    inner(z, 0)
+  }
+
+  override def foldRight[B](z: B)(op: (A, B) => B): B = {
+    @inline @tailrec def inner(acc: B, n: Int): B =
+      if (n == 0) acc
+      else inner(op(apply(n), acc), n - 1)
+
+    inner(z, length)
+  }
+}

algs4-scala/src/main/scala/org/gs/digraph/Topological.scala

@@ -22,13 +22,13 @@ class Topological[A <: DigraphMarker](g: A) {
         case d: Digraph             => new DepthFirstOrder(d)
         case e: EdgeWeightedDigraph => new EdgeWeightedDepthFirstOrder(e)
       }
-      Some(dfs.reversePost)
+      Some(dfs.reversePost())
     } else None
 
   private lazy val _order = createOrder(!finder.hasCycle)
 
   /** returns if it has a topological order */
-  def hasOrder(): Boolean = _order != None
+  def hasOrder(): Boolean = _order.isDefined
 
   /** returns list of vertex numbers in topological order */
   def order(): Option[List[Int]] = _order

build.sbt

@@ -2,7 +2,7 @@ import Commons._
 
 ThisBuild / version := "1.0.0"
 
-ThisBuild / scalaVersion := "2.13.1"
+ThisBuild / scalaVersion := "2.13.2"
 
 ThisBuild / shellPrompt := (s => Project.extract(s).currentProject.id + " > ")
 

leetcode/src/main/scala/leetcode/p100/P006ZigZagConversion.scala

@@ -0,0 +1,26 @@
+package leetcode.p100
+
+object P006ZigZagConversion {
+  def convert(s: String, numRows: Int): String = {
+    if (numRows < 2) return s
+
+    val bf = new StringBuilder()
+    val N = s.length
+    var i = 0
+    val cycleLen = 2 * numRows - 2
+    while (i < numRows) {
+      var j = 0
+      while (j + i < N) {
+        bf.addOne(s.charAt(j + i))
+        val IDX = j + cycleLen - i
+        if (i != 0 && i != numRows - 1 && IDX < N) {
+          bf.addOne(s.charAt(IDX))
+        }
+
+        j += cycleLen
+      }
+      i += 1
+    }
+    bf.toString()
+  }
+}

leetcode/src/test/scala/leetcode/p100/P006ZigZagConversionTest.scala

@@ -0,0 +1,13 @@
+package leetcode.p100
+
+import org.scalatest.matchers.should.Matchers
+import org.scalatest.wordspec.AnyWordSpec
+
+class P006ZigZagConversionTest extends AnyWordSpec with Matchers {
+  import P006ZigZagConversion._
+  val S = "PAYPALISHIRING"
+  "P006ZigZagConversionTest" should {
+    "convert1" in { convert(S, 3) shouldBe "PAHNAPLSIIGYIR" }
+    "convert2" in { convert(S, 4) shouldBe "PINALSIGYAHRPI" }
+  }
+}

project/build.properties

@@ -1 +1 @@
-sbt.version=1.3.8
+sbt.version=1.3.10

study-common/src/main/scala/study/Animal.scala

@@ -0,0 +1,25 @@
+package study
+
+sealed trait Animal
+
+class Cat extends Animal {
+  def meow(): Unit = println("meow")
+}
+
+class Dog extends Animal {
+  def woof(): Unit = println("woof")
+}
+
+object Animal {
+  def perform(animal: Animal): Unit = {
+    val func = animal match {
+      case cat: Cat => cat.meow _
+      case dog: Dog => dog.woof _
+    }
+    func.apply()
+  }
+
+  def main(args: Array[String]): Unit = {
+    perform(new Cat())
+  }
+}