Add triangle

config.json

@@ -228,6 +228,14 @@
         "prerequisites": [],
         "difficulty": 2
       },
+      {
+        "slug": "triangle",
+        "name": "Triangle",
+        "uuid": "54b9358f-0ce4-46d6-9a61-7eaf0b8d1bdc",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 2
+      },
       {
         "slug": "armstrong-numbers",
         "name": "Armstrong Numbers",

exercises/practice/triangle/.docs/instructions.md

@@ -0,0 +1,29 @@
+# Instructions
+
+Determine if a triangle is equilateral, isosceles, or scalene.
+
+An _equilateral_ triangle has all three sides the same length.
+
+An _isosceles_ triangle has at least two sides the same length.
+(It is sometimes specified as having exactly two sides the same length, but for the purposes of this exercise we'll say at least two.)
+
+A _scalene_ triangle has all sides of different lengths.
+
+## Note
+
+For a shape to be a triangle at all, all sides have to be of length > 0, and the sum of the lengths of any two sides must be greater than or equal to the length of the third side.
+
+In equations:
+
+Let `a`, `b`, and `c` be sides of the triangle.
+Then all three of the following expressions must be true:
+
+```text
+a + b ≥ c
+b + c ≥ a
+a + c ≥ b
+```
+
+See [Triangle Inequality][triangle-inequality]
+
+[triangle-inequality]: https://en.wikipedia.org/wiki/Triangle_inequality

exercises/practice/triangle/.meta/config.json

@@ -0,0 +1,22 @@
+{
+  "authors": [
+    "BNAndras"
+  ],
+  "files": {
+    "solution": [
+      "src/lib.cairo"
+    ],
+    "test": [
+      "tests/triangle.cairo"
+    ],
+    "example": [
+      ".meta/example.cairo"
+    ],
+    "invalidator": [
+      "Scarb.toml"
+    ]
+  },
+  "blurb": "Determine if a triangle is equilateral, isosceles, or scalene.",
+  "source": "The Ruby Koans triangle project, parts 1 & 2",
+  "source_url": "https://web.archive.org/web/20220831105330/http://rubykoans.com"
+}

exercises/practice/triangle/.meta/example.cairo

@@ -0,0 +1,37 @@
+pub fn is_equilateral(sides: [u64; 3]) -> bool {
+    is_triangle(@sides) && unique_sides(@sides) == 1
+}
+
+pub fn is_isosceles(sides: [u64; 3]) -> bool {
+    is_triangle(@sides) && unique_sides(@sides) < 3
+}
+
+pub fn is_scalene(sides: [u64; 3]) -> bool {
+    is_triangle(@sides) && unique_sides(@sides) == 3
+}
+
+fn unique_sides(sides: @[u64; 3]) -> u64 {
+    let [a, b, c] = sides;
+
+    if a == b && b == c {
+        1
+    } else if a == b || b == c || a == c {
+        2
+    } else {
+        3
+    }
+}
+
+fn is_triangle(sides: @[u64; 3]) -> bool {
+    let [a, b, c] = sides;
+
+    all_sides_positive(a, b, c) && satisifies_inequality(a, b, c)
+}
+
+fn all_sides_positive(a: @u64, b: @u64, c: @u64) -> bool {
+    *a > 0 && *b > 0 && *c > 0
+}
+
+fn satisifies_inequality(a: @u64, b: @u64, c: @u64) -> bool {
+    *a + *b > *c && *a + *c > *b && *b + *c > *a
+}

exercises/practice/triangle/.meta/tests.toml

@@ -0,0 +1,76 @@
+# 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.
+
+[8b2c43ac-7257-43f9-b552-7631a91988af]
+description = "equilateral triangle -> all sides are equal"
+
+[33eb6f87-0498-4ccf-9573-7f8c3ce92b7b]
+description = "equilateral triangle -> any side is unequal"
+
+[c6585b7d-a8c0-4ad8-8a34-e21d36f7ad87]
+description = "equilateral triangle -> no sides are equal"
+
+[16e8ceb0-eadb-46d1-b892-c50327479251]
+description = "equilateral triangle -> all zero sides is not a triangle"
+
+[3022f537-b8e5-4cc1-8f12-fd775827a00c]
+description = "equilateral triangle -> sides may be floats"
+include = false
+
+[cbc612dc-d75a-4c1c-87fc-e2d5edd70b71]
+description = "isosceles triangle -> last two sides are equal"
+
+[e388ce93-f25e-4daf-b977-4b7ede992217]
+description = "isosceles triangle -> first two sides are equal"
+
+[d2080b79-4523-4c3f-9d42-2da6e81ab30f]
+description = "isosceles triangle -> first and last sides are equal"
+
+[8d71e185-2bd7-4841-b7e1-71689a5491d8]
+description = "isosceles triangle -> equilateral triangles are also isosceles"
+
+[840ed5f8-366f-43c5-ac69-8f05e6f10bbb]
+description = "isosceles triangle -> no sides are equal"
+
+[2eba0cfb-6c65-4c40-8146-30b608905eae]
+description = "isosceles triangle -> first triangle inequality violation"
+
+[278469cb-ac6b-41f0-81d4-66d9b828f8ac]
+description = "isosceles triangle -> second triangle inequality violation"
+
+[90efb0c7-72bb-4514-b320-3a3892e278ff]
+description = "isosceles triangle -> third triangle inequality violation"
+
+[adb4ee20-532f-43dc-8d31-e9271b7ef2bc]
+description = "isosceles triangle -> sides may be floats"
+include = false
+
+[e8b5f09c-ec2e-47c1-abec-f35095733afb]
+description = "scalene triangle -> no sides are equal"
+
+[2510001f-b44d-4d18-9872-2303e7977dc1]
+description = "scalene triangle -> all sides are equal"
+
+[c6e15a92-90d9-4fb3-90a2-eef64f8d3e1e]
+description = "scalene triangle -> first and second sides are equal"
+
+[3da23a91-a166-419a-9abf-baf4868fd985]
+description = "scalene triangle -> first and third sides are equal"
+
+[b6a75d98-1fef-4c42-8e9a-9db854ba0a4d]
+description = "scalene triangle -> second and third sides are equal"
+
+[70ad5154-0033-48b7-af2c-b8d739cd9fdc]
+description = "scalene triangle -> may not violate triangle inequality"
+
+[26d9d59d-f8f1-40d3-ad58-ae4d54123d7d]
+description = "scalene triangle -> sides may be floats"
+include = false

exercises/practice/triangle/Scarb.toml

@@ -0,0 +1,7 @@
+[package]
+name = "triangle"
+version = "0.1.0"
+edition = "2024_07"
+
+[dev-dependencies]
+cairo_test = "2.7.1"

exercises/practice/triangle/src/lib.cairo

@@ -0,0 +1,11 @@
+pub fn is_equilateral(sides: [u64; 3]) -> bool {
+    panic!("implement `is_equilateral`")
+}
+
+pub fn is_isosceles(sides: [u64; 3]) -> bool {
+    panic!("implement `is_isosceles`")
+}
+
+pub fn is_scalene(sides: [u64; 3]) -> bool {
+    panic!("implement `is_scalene`")
+}

exercises/practice/triangle/tests/triangle.cairo

@@ -0,0 +1,132 @@
+use triangle::{is_equilateral, is_isosceles, is_scalene};
+
+// Equilateral triangles
+
+#[test]
+fn equilateral_all_sides_are_equal() {
+    let sides: [u64; 3] = [2, 2, 2];
+    assert!(is_equilateral(sides));
+}
+
+#[test]
+#[ignore]
+fn equilateral_any_side_is_unequal() {
+    let sides: [u64; 3] = [2, 3, 2];
+    assert!(!is_equilateral(sides));
+}
+
+#[test]
+#[ignore]
+fn equilateral_no_sides_are_equal() {
+    let sides: [u64; 3] = [5, 4, 6];
+    assert!(!is_equilateral(sides));
+}
+
+#[test]
+#[ignore]
+fn equilateral_all_zero_sides_is_not_a_triangle() {
+    let sides: [u64; 3] = [0, 0, 0];
+    assert!(!is_equilateral(sides));
+}
+
+// Isosceles triangles
+
+#[test]
+#[ignore]
+fn isosceles_last_two_sides_are_equal() {
+    let sides: [u64; 3] = [3, 4, 4];
+    assert!(is_isosceles(sides));
+}
+
+#[test]
+#[ignore]
+fn isosceles_first_two_sides_are_equal() {
+    let sides: [u64; 3] = [4, 4, 3];
+    assert!(is_isosceles(sides));
+}
+
+#[test]
+#[ignore]
+fn isosceles_first_and_last_sides_are_equal() {
+    let sides: [u64; 3] = [4, 3, 4];
+    assert!(is_isosceles(sides));
+}
+
+#[test]
+#[ignore]
+fn isosceles_equilateral_triangles_are_also_isosceles() {
+    let sides: [u64; 3] = [4, 4, 4];
+    assert!(is_isosceles(sides));
+}
+
+#[test]
+#[ignore]
+fn isosceles_no_sides_are_equal() {
+    let sides: [u64; 3] = [2, 3, 4];
+    assert!(!is_isosceles(sides));
+}
+
+#[test]
+#[ignore]
+fn isosceles_first_triangle_inequality_violation() {
+    let sides: [u64; 3] = [1, 1, 3];
+    assert!(!is_isosceles(sides));
+}
+
+#[test]
+#[ignore]
+fn isosceles_second_triangle_inequality_violation() {
+    let sides: [u64; 3] = [1, 3, 1];
+    assert!(!is_isosceles(sides));
+}
+
+#[test]
+#[ignore]
+fn isosceles_third_triangle_inequality_violation() {
+    let sides: [u64; 3] = [3, 1, 1];
+    assert!(!is_isosceles(sides));
+}
+
+// Scalene triangles
+
+#[test]
+#[ignore]
+fn scalene_no_sides_are_equal() {
+    let sides: [u64; 3] = [5, 4, 6];
+    assert!(is_scalene(sides));
+}
+
+#[test]
+#[ignore]
+fn scalene_all_sides_are_equal() {
+    let sides: [u64; 3] = [4, 4, 4];
+    assert!(!is_scalene(sides));
+}
+
+#[test]
+#[ignore]
+fn scalene_first_and_second_sides_are_equal() {
+    let sides: [u64; 3] = [4, 4, 3];
+    assert!(!is_scalene(sides));
+}
+
+#[test]
+#[ignore]
+fn scalene_first_and_third_sides_are_equal() {
+    let sides: [u64; 3] = [3, 4, 3];
+    assert!(!is_scalene(sides));
+}
+
+#[test]
+#[ignore]
+fn scalene_second_and_third_sides_are_equal() {
+    let sides: [u64; 3] = [4, 3, 3];
+    assert!(!is_scalene(sides));
+}
+
+#[test]
+#[ignore]
+fn scalene_may_not_violate_triangle_inequality() {
+    let sides: [u64; 3] = [7, 3, 2];
+    assert!(!is_scalene(sides));
+}