Extract isSorted to library

Author: sim642

src/main/scala/eu/sim642/adventofcode2019/Day4.scala

@@ -1,5 +1,7 @@
 package eu.sim642.adventofcode2019
 
+import eu.sim642.adventofcodelib.SeqImplicits._
+
 import scala.Integral.Implicits._
 import scala.annotation.tailrec
 
@@ -43,23 +45,19 @@ object Day4 {
     }
   }
 
-  def isSorted(list: List[Int]): Boolean = {
-    (list lazyZip list.tail).forall(_ <= _)
-  }
-
   object Part1 extends Part {
     override def isPassword(number: Int): Boolean = {
       val digits = toDigitList(number)
       // seems a bit faster to short-circuit isSorted first
-      isSorted(digits) && runLengthsReverse(digits).exists(_ >= 2)
+      digits.isSorted && runLengthsReverse(digits).exists(_ >= 2)
     }
   }
 
   object Part2 extends Part {
     override def isPassword(number: Int): Boolean = {
       val digits = toDigitList(number)
       // seems a bit faster to short-circuit isSorted first
-      isSorted(digits) && runLengthsReverse(digits).contains(2)
+      digits.isSorted && runLengthsReverse(digits).contains(2)
     }
   }
 

src/main/scala/eu/sim642/adventofcode2024/Day2.scala

@@ -1,6 +1,7 @@
 package eu.sim642.adventofcode2024
 
 import eu.sim642.adventofcodelib.IteratorImplicits._
+import eu.sim642.adventofcodelib.SeqImplicits._
 
 object Day2 {
 
@@ -15,8 +16,8 @@ object Day2 {
   object Part1 extends Part {
     override def isSafe(report: Report): Boolean = {
       val sorted = report.sorted
-      val increasing = report == sorted // TODO: add isSorted to library
-      val decreasing = report.reverse == sorted // TODO: add isSorted to library (with Ordering)
+      val increasing = report.isSorted
+      val decreasing = report.isSorted(using Ordering[Int].reverse)
       val monotonic = increasing || decreasing
       val safeDifferences = report.iterator.zipWithTail.forall({ case (a, b) =>
         (1 to 3).contains((a - b).abs)

src/main/scala/eu/sim642/adventofcodelib/SeqImplicits.scala

@@ -1,12 +1,18 @@
 package eu.sim642.adventofcodelib
 
 import eu.sim642.adventofcodelib.IntegralImplicits._
+import IteratorImplicits._
 
 import scala.collection.BuildFrom
 import scala.collection.generic.IsSeq
 
 object SeqImplicits {
 
+  extension [A](seq: Seq[A]) {
+    def isSorted(using ord: Ordering[A]): Boolean =
+      seq.iterator.zipWithTail.forall(ord.lteq)
+  }
+
   extension [Repr](coll: Repr)(using seq: IsSeq[Repr]) {
     def rotateLeft[That](n: Int)(using bf: BuildFrom[Repr, seq.A, That]): That = {
       val seqOps = seq(coll)