Add resistor color trio (#863)

Author: Sencudra

config.json

@@ -795,6 +795,14 @@
         "prerequisites": [],
         "difficulty": 3
       },
+      {
+        "slug": "resistor-color-trio",
+        "name": "Resistor Color Trio",
+        "uuid": "bfd64381-b035-46e5-827b-99ed8b674cde",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 3
+      },
       {
         "slug": "acronym",
         "name": "Acronym",

exercises/practice/resistor-color-trio/.docs/instructions.md

@@ -0,0 +1,56 @@
+# Instructions
+
+If you want to build something using a Raspberry Pi, you'll probably use _resistors_.
+For this exercise, you need to know only three things about them:
+
+- Each resistor has a resistance value.
+- Resistors are small - so small in fact that if you printed the resistance value on them, it would be hard to read.
+  To get around this problem, manufacturers print color-coded bands onto the resistors to denote their resistance values.
+- Each band acts as a digit of a number.
+  For example, if they printed a brown band (value 1) followed by a green band (value 5), it would translate to the number 15.
+  In this exercise, you are going to create a helpful program so that you don't have to remember the values of the bands.
+  The program will take 3 colors as input, and outputs the correct value, in ohms.
+  The color bands are encoded as follows:
+
+- black: 0
+- brown: 1
+- red: 2
+- orange: 3
+- yellow: 4
+- green: 5
+- blue: 6
+- violet: 7
+- grey: 8
+- white: 9
+
+In Resistor Color Duo you decoded the first two colors.
+For instance: orange-orange got the main value `33`.
+The third color stands for how many zeros need to be added to the main value.
+The main value plus the zeros gives us a value in ohms.
+For the exercise it doesn't matter what ohms really are.
+For example:
+
+- orange-orange-black would be 33 and no zeros, which becomes 33 ohms.
+- orange-orange-red would be 33 and 2 zeros, which becomes 3300 ohms.
+- orange-orange-orange would be 33 and 3 zeros, which becomes 33000 ohms.
+
+(If Math is your thing, you may want to think of the zeros as exponents of 10.
+If Math is not your thing, go with the zeros.
+It really is the same thing, just in plain English instead of Math lingo.)
+
+This exercise is about translating the colors into a label:
+
+> "... ohms"
+
+So an input of `"orange", "orange", "black"` should return:
+
+> "33 ohms"
+
+When we get to larger resistors, a [metric prefix][metric-prefix] is used to indicate a larger magnitude of ohms, such as "kiloohms".
+That is similar to saying "2 kilometers" instead of "2000 meters", or "2 kilograms" for "2000 grams".
+
+For example, an input of `"orange", "orange", "orange"` should return:
+
+> "33 kiloohms"
+
+[metric-prefix]: https://en.wikipedia.org/wiki/Metric_prefix

exercises/practice/resistor-color-trio/.meta/Sources/ResistorColorTrio/ResistorColorTrioExample.swift

@@ -0,0 +1,86 @@
+import Foundation
+
+enum Color: String, CaseIterable {
+    case black
+    case brown
+    case red
+    case orange
+    case yellow
+    case green
+    case blue
+    case violet
+    case grey
+    case white
+}
+
+enum Unit: String {
+    case ohms
+    case kiloohms
+    case megaohms
+    case gigaohms
+}
+
+enum ResistorColorTrioError: Error {
+    case invalidInput
+    case unknownColor
+}
+
+enum ResistorColorTrio {
+
+    static func label(for colors: [String]) throws -> String {
+        guard colors.count >= 3 else {
+            throw ResistorColorTrioError.invalidInput
+        }
+
+        let convertedColors = try colors.reduce(into: [Color]()) { partialResult, string in
+            guard let color = Color(rawValue: string) else {
+                throw ResistorColorTrioError.unknownColor
+            }
+            partialResult.append(color)
+        }
+
+        var zeros = 0
+        var value = 0
+        let firstDigit = code(for: convertedColors[0])
+        if (firstDigit > 0) {
+            value += firstDigit
+        }
+
+        let secondDigit = code(for: convertedColors[1])
+        if (secondDigit == 0) {
+            zeros += 1
+        }
+        else {
+            value = value * 10 + secondDigit
+        }
+
+        zeros += code(for: convertedColors[2])
+        let (remaining, unit) = strip(zeros)
+        return "\(value * Int(pow(10.0, Double(remaining)))) \(unit)"
+    }
+
+    private static func strip(_ zeros: Int) -> (remaining: Int, unit: String) {
+        switch zeros {
+            case 0, 1, 2: return (zeros % 3, Unit.ohms.rawValue)
+            case 3, 4, 5: return (zeros % 3, Unit.kiloohms.rawValue)
+            case 6, 7, 8: return (zeros % 3, Unit.megaohms.rawValue)
+            case 9: return (0, Unit.gigaohms.rawValue)
+            default: return (0, Unit.ohms.rawValue)            
+        }
+    }
+}
+
+fileprivate func code(for color: Color) -> Int {
+    switch color {
+        case .black: return 0
+        case .brown: return 1
+        case .red: return 2
+        case .orange: return 3
+        case .yellow: return 4
+        case .green: return 5
+        case .blue: return 6
+        case .violet: return 7
+        case .grey: return 8
+        case .white: return 9
+    }
+}

exercises/practice/resistor-color-trio/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "Sencudra"
+  ],
+  "files": {
+    "solution": [
+      "Sources/ResistorColorTrio/ResistorColorTrio.swift"
+    ],
+    "test": [
+      "Tests/ResistorColorTrioTests/ResistorColorTrioTests.swift"
+    ],
+    "example": [
+      ".meta/Sources/ResistorColorTrio/ResistorColorTrioExample.swift"
+    ]
+  },
+  "blurb": "Convert color codes, as used on resistors, to a human-readable label.",
+  "source": "Maud de Vries, Erik Schierboom",
+  "source_url": "https://github.com/exercism/problem-specifications/issues/1549"
+}

exercises/practice/resistor-color-trio/.meta/template.swift

@@ -0,0 +1,18 @@
+import Testing
+import Foundation
+@testable import {{ exercise | camelCase }}
+
+let RUNALL = Bool(ProcessInfo.processInfo.environment["RUNALL", default: "false"]) ?? false
+
+@Suite struct {{ exercise | camelCase }}Tests {
+    {% for case in cases %}
+    {% if forloop.first -%}
+        @Test("{{case.description}}")
+    {% else -%}
+        @Test("{{case.description}}", .enabled(if: RUNALL))
+    {% endif -%}
+    func test{{ case.description | camelCase }}() throws {
+        #expect(try ResistorColorTrio.{{ case.property }}(for: {{ case.input.colors | toStringArray }}) == "{{ case.expected.value }} {{case.expected.unit}}")
+    }
+    {% endfor -%}
+}

exercises/practice/resistor-color-trio/.meta/tests.toml

@@ -0,0 +1,40 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[d6863355-15b7-40bb-abe0-bfb1a25512ed]
+description = "Orange and orange and black"
+
+[1224a3a9-8c8e-4032-843a-5224e04647d6]
+description = "Blue and grey and brown"
+
+[b8bda7dc-6b95-4539-abb2-2ad51d66a207]
+description = "Red and black and red"
+
+[5b1e74bc-d838-4eda-bbb3-eaba988e733b]
+description = "Green and brown and orange"
+
+[f5d37ef9-1919-4719-a90d-a33c5a6934c9]
+description = "Yellow and violet and yellow"
+
+[5f6404a7-5bb3-4283-877d-3d39bcc33854]
+description = "Blue and violet and blue"
+
+[7d3a6ab8-e40e-46c3-98b1-91639fff2344]
+description = "Minimum possible value"
+
+[ca0aa0ac-3825-42de-9f07-dac68cc580fd]
+description = "Maximum possible value"
+
+[0061a76c-903a-4714-8ce2-f26ce23b0e09]
+description = "First two colors make an invalid octal number"
+
+[30872c92-f567-4b69-a105-8455611c10c4]
+description = "Ignore extra colors"

exercises/practice/resistor-color-trio/Package.swift

@@ -0,0 +1,21 @@
+// swift-tools-version:6.0
+
+import PackageDescription
+
+let package = Package(
+  name: "ResistorColorTrio",
+  products: [
+    .library(
+      name: "ResistorColorTrio",
+      targets: ["ResistorColorTrio"])
+  ],
+  dependencies: [],
+  targets: [
+    .target(
+      name: "ResistorColorTrio",
+      dependencies: []),
+    .testTarget(
+      name: "ResistorColorTrioTests",
+      dependencies: ["ResistorColorTrio"]),
+  ]
+)

exercises/practice/resistor-color-trio/Sources/ResistorColorTrio/ResistorColorTrio.swift

@@ -0,0 +1,5 @@
+import Foundation
+
+enum ResistorColorTrio {
+    // Write your code for the 'ResistorColorTrio' exercise in this file.
+}

exercises/practice/resistor-color-trio/Tests/ResistorColorTrioTests/ResistorColorTrioTests.swift

@@ -0,0 +1,60 @@
+import Foundation
+import Testing
+
+@testable import ResistorColorTrio
+
+let RUNALL = Bool(ProcessInfo.processInfo.environment["RUNALL", default: "false"]) ?? false
+
+@Suite struct ResistorColorTrioTests {
+
+  @Test("Orange and orange and black")
+  func testOrangeAndOrangeAndBlack() throws {
+    #expect(try ResistorColorTrio.label(for: ["orange", "orange", "black"]) == "33 ohms")
+  }
+
+  @Test("Blue and grey and brown", .enabled(if: RUNALL))
+  func testBlueAndGreyAndBrown() throws {
+    #expect(try ResistorColorTrio.label(for: ["blue", "grey", "brown"]) == "680 ohms")
+  }
+
+  @Test("Red and black and red", .enabled(if: RUNALL))
+  func testRedAndBlackAndRed() throws {
+    #expect(try ResistorColorTrio.label(for: ["red", "black", "red"]) == "2 kiloohms")
+  }
+
+  @Test("Green and brown and orange", .enabled(if: RUNALL))
+  func testGreenAndBrownAndOrange() throws {
+    #expect(try ResistorColorTrio.label(for: ["green", "brown", "orange"]) == "51 kiloohms")
+  }
+
+  @Test("Yellow and violet and yellow", .enabled(if: RUNALL))
+  func testYellowAndVioletAndYellow() throws {
+    #expect(try ResistorColorTrio.label(for: ["yellow", "violet", "yellow"]) == "470 kiloohms")
+  }
+
+  @Test("Blue and violet and blue", .enabled(if: RUNALL))
+  func testBlueAndVioletAndBlue() throws {
+    #expect(try ResistorColorTrio.label(for: ["blue", "violet", "blue"]) == "67 megaohms")
+  }
+
+  @Test("Minimum possible value", .enabled(if: RUNALL))
+  func testMinimumPossibleValue() throws {
+    #expect(try ResistorColorTrio.label(for: ["black", "black", "black"]) == "0 ohms")
+  }
+
+  @Test("Maximum possible value", .enabled(if: RUNALL))
+  func testMaximumPossibleValue() throws {
+    #expect(try ResistorColorTrio.label(for: ["white", "white", "white"]) == "99 gigaohms")
+  }
+
+  @Test("First two colors make an invalid octal number", .enabled(if: RUNALL))
+  func testFirstTwoColorsMakeAnInvalidOctalNumber() throws {
+    #expect(try ResistorColorTrio.label(for: ["black", "grey", "black"]) == "8 ohms")
+  }
+
+  @Test("Ignore extra colors", .enabled(if: RUNALL))
+  func testIgnoreExtraColors() throws {
+    #expect(
+      try ResistorColorTrio.label(for: ["blue", "green", "yellow", "orange"]) == "650 kiloohms")
+  }
+}