A 3D vector implementation

With
* addition
* subtraction
* absolute
* taxi distance (= Manhattan distance)
* scalar multiplication with Int and Long

Author: rhaendel

src/main/kotlin/de/ronny_h/aoc/extensions/threedim/Vector.kt

@@ -0,0 +1,18 @@
+package de.ronny_h.aoc.extensions.threedim
+
+import kotlin.math.abs
+import kotlin.math.cbrt
+
+data class Vector(val x: Long, val y: Long, val z: Long) {
+    companion object {
+        val ZERO = Vector(0, 0, 0)
+    }
+
+    operator fun plus(other: Vector) = Vector(x + other.x, y + other.y, z + other.z)
+    operator fun minus(other: Vector) = Vector(x - other.x, y - other.y, z - other.z)
+    infix fun taxiDistanceTo(other: Vector): Long = abs(other.x - x) + abs(other.y - y) + abs(other.z - z)
+    fun abs(): Double = cbrt(x * x.toDouble() + y * y.toDouble() + z * z.toDouble())
+}
+
+operator fun Int.times(vector: Vector) = Vector(this * vector.x, this * vector.y, this * vector.z)
+operator fun Long.times(vector: Vector) = Vector(this * vector.x, this * vector.y, this * vector.z)

src/test/kotlin/de/ronny_h/aoc/extensions/threedim/VectorTest.kt

@@ -0,0 +1,68 @@
+package de.ronny_h.aoc.extensions.threedim
+
+import de.ronny_h.aoc.extensions.threedim.Vector.Companion.ZERO
+import io.kotest.core.spec.style.StringSpec
+import io.kotest.data.forAll
+import io.kotest.data.row
+import io.kotest.matchers.shouldBe
+
+class VectorTest : StringSpec({
+    "vectors can be added" {
+        forAll(
+            row(Vector(0, 0, 0), Vector(0, 0, 0), Vector(0, 0, 0)),
+            row(Vector(10, 20, 30), Vector(1, 2, 3), Vector(11, 22, 33)),
+            row(Vector(10, 20, 30), Vector(-1, -2, -3), Vector(9, 18, 27)),
+        ) { a, b, sum ->
+            a + b shouldBe sum
+        }
+    }
+
+    "vectors can be subtracted" {
+        forAll(
+            row(Vector(0, 0, 0), Vector(0, 0, 0), Vector(0, 0, 0)),
+            row(Vector(10, 20, 30), Vector(1, 2, 3), Vector(9, 18, 27)),
+            row(Vector(10, 20, 30), Vector(-1, -2, -3), Vector(11, 22, 33)),
+        ) { a, b, difference ->
+            a - b shouldBe difference
+        }
+    }
+
+    "the taxi distance of vectors" {
+        forAll(
+            row(Vector(0, 0, 0), Vector(0, 0, 0), 0),
+            row(Vector(10, 20, 30), Vector(11, 22, 33), 6),
+            row(Vector(10, 20, 30), Vector(9, 18, 27), 6),
+        ) { a, b, distance ->
+            a taxiDistanceTo b shouldBe distance
+        }
+    }
+
+    "the absolute of a vector" {
+        forAll(
+            row(Vector(0, 0, 0), 0.0),
+            row(Vector(3, 3, 3), 3.0),
+        ) { v, absolute ->
+            v.abs() shouldBe absolute
+        }
+    }
+
+    "scalar multiplication with an Int" {
+        forAll(
+            row(0, Vector(1, 2, 3), ZERO),
+            row(1, Vector(1, 2, 3), Vector(1, 2, 3)),
+            row(10, Vector(1, 2, 3), Vector(10, 20, 30)),
+        ) { a, v, product ->
+            a * v shouldBe product
+        }
+    }
+
+    "scalar multiplication with a Long" {
+        forAll(
+            row(0L, Vector(1, 2, 3), ZERO),
+            row(1L, Vector(1, 2, 3), Vector(1, 2, 3)),
+            row(10L, Vector(1, 2, 3), Vector(10, 20, 30)),
+        ) { a, v, product ->
+            a * v shouldBe product
+        }
+    }
+})