From 54a77fa1a2211eb01f7af7d013a429f2cc9af540 Mon Sep 17 00:00:00 2001
From: twentylemon <taras.mychaskiw@gmail.com>
Date: Tue, 24 Dec 2024 23:48:56 -0500
Subject: [PATCH] =?UTF-8?q?=E2=9C=A8=20add=20`cartesianProduct`;=20combine?=
 =?UTF-8?q?=20`combinations`=20file=20into=20`collections`?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../org/lemon/advent/lib/collections.scala    | 36 +++++++++++++++++++
 .../org/lemon/advent/lib/combinations.scala   | 28 ---------------
 2 files changed, 36 insertions(+), 28 deletions(-)
 delete mode 100644 src/main/scala/org/lemon/advent/lib/combinations.scala

diff --git a/src/main/scala/org/lemon/advent/lib/collections.scala b/src/main/scala/org/lemon/advent/lib/collections.scala
index 66d88d0..3091462 100644
--- a/src/main/scala/org/lemon/advent/lib/collections.scala
+++ b/src/main/scala/org/lemon/advent/lib/collections.scala
@@ -15,3 +15,39 @@ extension [A](it: Iterator[A])
     * @return the nth element of the iterator, or None if there is no nth element
     */
   def nthOption(n: Int): Option[A] = it.drop(n).nextOption
+
+extension [A](it: Iterable[A])
+  /** Returns an iterator view of the Cartesian product of this iterable and another.
+    * Also known as the cross product
+    *
+    * @param rhs the other iterable
+    * @return all pairs of elements (a, b) where a is from this iterable and b is from the other iterable
+    */
+  def cartesianProduct[B](rhs: Iterable[B]): Iterator[(A, B)] =
+    for a <- it.iterator; b <- rhs.iterator yield (a, b)
+
+  /** Returns an iterator of all unordered pairs of elements in the iterable.
+    * If the collection contains duplicates, the pairs will not be unique.
+    *
+    * @return iterator of all unordered pairs
+    */
+  def pairs: Iterator[(A, A)] =
+    for
+      (x, i) <- it.iterator.zipWithIndex
+      (y, j) <- it.iterator.zipWithIndex
+      if i < j
+    yield (x, y)
+
+  /** Returns an iterator of all unordered triples of elements in the iterable.
+    * If the collection contains duplicates, the triples will not be unique.
+    *
+    * @return iterator of all unordered triples
+    */
+  def triples: Iterator[(A, A, A)] =
+    for
+      (x, i) <- it.iterator.zipWithIndex
+      (y, j) <- it.iterator.zipWithIndex
+      (z, k) <- it.iterator.zipWithIndex
+      if i < j
+      if j < k
+    yield (x, y, z)
diff --git a/src/main/scala/org/lemon/advent/lib/combinations.scala b/src/main/scala/org/lemon/advent/lib/combinations.scala
deleted file mode 100644
index e95942c..0000000
--- a/src/main/scala/org/lemon/advent/lib/combinations.scala
+++ /dev/null
@@ -1,28 +0,0 @@
-package org.lemon.advent.lib
-
-extension [T](xs: Iterable[T])
-  /** Returns an iterator of all unordered pairs of elements in the iterable.
-    * If the collection contains duplicates, the pairs will not be unique.
-    *
-    * @return iterator of all unordered pairs
-    */
-  def pairs: Iterator[(T, T)] =
-    for
-      (x, i) <- xs.iterator.zipWithIndex
-      (y, j) <- xs.iterator.zipWithIndex
-      if i < j
-    yield (x, y)
-
-  /** Returns an iterator of all unordered triples of elements in the iterable.
-    * If the collection contains duplicates, the triples will not be unique.
-    *
-    * @return iterator of all unordered triples
-    */
-  def triples: Iterator[(T, T, T)] =
-    for
-      (x, i) <- xs.iterator.zipWithIndex
-      (y, j) <- xs.iterator.zipWithIndex
-      (z, k) <- xs.iterator.zipWithIndex
-      if i < j
-      if j < k
-    yield (x, y, z)