Add pascals-triangle exercise

config.json

@@ -493,6 +493,14 @@
           "integers"
         ]
       },
+      {
+        "slug": "pascals-triangle",
+        "name": "Pascals Triangle",
+        "uuid": "2de80883-1847-4fbe-aa33-0b773f356273",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 4
+      },
       {
         "slug": "dnd-character",
         "name": "D&D Character",

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

@@ -0,0 +1,14 @@
+# Instructions
+
+Compute Pascal's triangle up to a given number of rows.
+
+In Pascal's Triangle each number is computed by adding the numbers to the right and left of the current position in the previous row.
+
+```text
+    1
+   1 1
+  1 2 1
+ 1 3 3 1
+1 4 6 4 1
+# ... etc
+```

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

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "keiravillekode"
+  ],
+  "files": {
+    "solution": [
+      "source/pascals_triangle.d"
+    ],
+    "test": [
+      "source/pascals_triangle.d"
+    ],
+    "example": [
+      "example/pascals_triangle.d"
+    ]
+  },
+  "blurb": "Compute Pascal's triangle up to a given number of rows.",
+  "source": "Pascal's Triangle at Wolfram Math World",
+  "source_url": "https://www.wolframalpha.com/input/?i=Pascal%27s+triangle"
+}

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

@@ -0,0 +1,34 @@
+# 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.
+
+[9920ce55-9629-46d5-85d6-4201f4a4234d]
+description = "zero rows"
+
+[70d643ce-a46d-4e93-af58-12d88dd01f21]
+description = "single row"
+
+[a6e5a2a2-fc9a-4b47-9f4f-ed9ad9fbe4bd]
+description = "two rows"
+
+[97206a99-79ba-4b04-b1c5-3c0fa1e16925]
+description = "three rows"
+
+[565a0431-c797-417c-a2c8-2935e01ce306]
+description = "four rows"
+
+[06f9ea50-9f51-4eb2-b9a9-c00975686c27]
+description = "five rows"
+
+[c3912965-ddb4-46a9-848e-3363e6b00b13]
+description = "six rows"
+
+[6cb26c66-7b57-4161-962c-81ec8c99f16b]
+description = "ten rows"

exercises/practice/pascals-triangle/dub.sdl

@@ -0,0 +1,2 @@
+name "pascals-triangle"
+buildRequirements "disallowDeprecations"

exercises/practice/pascals-triangle/example/pascals_triangle.d

@@ -0,0 +1,20 @@
+module pascals_triangle;
+
+pure int[][] rows(int count)
+{
+    int[][] result = new int[][](count);
+    int[] previous;
+    for (int i = 0; i < count; ++i)
+    {
+        int[] current = new int[](i + 1);
+        current[0] = 1;
+        for (int j = 1; j < i; ++j)
+        {
+            current[j] = previous[j - 1] + previous[j];
+        }
+        current[i] = 1;
+        result[i] = current;
+        previous = current;
+    }
+    return result;
+}

exercises/practice/pascals-triangle/source/pascals_triangle.d

@@ -0,0 +1,101 @@
+module pascals_triangle;
+
+pure int[][] rows(int count)
+{
+    // implement this function
+}
+
+unittest
+{
+    immutable int allTestsEnabled = 0;
+
+    // Zero rows
+    {
+        int[][] expected = [
+        ];
+        assert(rows(0) == expected);
+    }
+
+    static if (allTestsEnabled)
+    {
+        // Single row
+        {
+            int[][] expected = [
+                [1],
+            ];
+            assert(rows(1) == expected);
+        }
+
+        // Two rows
+        {
+            int[][] expected = [
+                [1],
+                [1, 1],
+            ];
+            assert(rows(2) == expected);
+        }
+
+        // Three rows
+        {
+            int[][] expected = [
+                [1],
+                [1, 1],
+                [1, 2, 1],
+            ];
+            assert(rows(3) == expected);
+        }
+
+        // Four rows
+        {
+            int[][] expected = [
+                [1],
+                [1, 1],
+                [1, 2, 1],
+                [1, 3, 3, 1],
+            ];
+            assert(rows(4) == expected);
+        }
+
+        // Five rows
+        {
+            int[][] expected = [
+                [1],
+                [1, 1],
+                [1, 2, 1],
+                [1, 3, 3, 1],
+                [1, 4, 6, 4, 1],
+            ];
+            assert(rows(5) == expected);
+        }
+
+        // Six rows
+        {
+            int[][] expected = [
+                [1],
+                [1, 1],
+                [1, 2, 1],
+                [1, 3, 3, 1],
+                [1, 4, 6, 4, 1],
+                [1, 5, 10, 10, 5, 1],
+            ];
+            assert(rows(6) == expected);
+        }
+
+        // Ten rows
+        {
+            int[][] expected = [
+                [1],
+                [1, 1],
+                [1, 2, 1],
+                [1, 3, 3, 1],
+                [1, 4, 6, 4, 1],
+                [1, 5, 10, 10, 5, 1],
+                [1, 6, 15, 20, 15, 6, 1],
+                [1, 7, 21, 35, 35, 21, 7, 1],
+                [1, 8, 28, 56, 70, 56, 28, 8, 1],
+                [1, 9, 36, 84, 126, 126, 84, 36, 9, 1],
+            ];
+            assert(rows(10) == expected);
+        }
+    }
+}