Add transpose exercise (#267)

config.json

@@ -276,6 +276,15 @@
           "math"
         ]
       },
+      {
+        "slug": "transpose",
+        "name": "Transpose",
+        "uuid": "5184de5a-4772-4389-aa3c-b1117b601450",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5,
+        "topics": []
+      },
       {
         "slug": "perfect-numbers",
         "name": "Perfect Numbers",

exercises/practice/transpose/.docs/instructions.md

@@ -0,0 +1,61 @@
+# Instructions
+
+Given an input text output it transposed.
+
+Roughly explained, the transpose of a matrix:
+
+```text
+ABC
+DEF
+```
+
+is given by:
+
+```text
+AD
+BE
+CF
+```
+
+Rows become columns and columns become rows.
+See [transpose][].
+
+If the input has rows of different lengths, this is to be solved as follows:
+
+- Pad to the left with spaces.
+- Don't pad to the right.
+
+Therefore, transposing this matrix:
+
+```text
+ABC
+DE
+```
+
+results in:
+
+```text
+AD
+BE
+C
+```
+
+And transposing:
+
+```text
+AB
+DEF
+```
+
+results in:
+
+```text
+AD
+BE
+ F
+```
+
+In general, all characters from the input should also be present in the transposed output.
+That means that if a column in the input text contains only spaces on its bottom-most row(s), the corresponding output row should contain the spaces in its right-most column(s).
+
+[transpose]: https://en.wikipedia.org/wiki/Transpose

exercises/practice/transpose/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "keiravillekode"
+  ],
+  "files": {
+    "solution": [
+      "transpose.sml"
+    ],
+    "test": [
+      "test.sml"
+    ],
+    "example": [
+      ".meta/example.sml"
+    ]
+  },
+  "blurb": "Take input text and output it transposed.",
+  "source": "Reddit r/dailyprogrammer challenge #270 [Easy].",
+  "source_url": "https://web.archive.org/web/20230630051421/https://old.reddit.com/r/dailyprogrammer/comments/4msu2x/challenge_270_easy_transpose_the_input_text/"
+}

exercises/practice/transpose/.meta/example.sml

@@ -0,0 +1,29 @@
+fun transpose (lines: string list): string list =
+  let
+    fun spaces (n: int): string =
+      if n = 0 then ""
+      else " " ^ spaces (n -1)
+
+    fun generateLine (index: int): string =
+      let
+        fun recurse (gap: int) (remaining: string list): string =
+          case remaining of
+              nil => ""
+            | first :: rest =>
+                if index >= size first then recurse (gap + 1) rest
+                else (spaces gap) ^ (String.substring(first, index, 1)) ^ (recurse 0 rest)
+      in
+        recurse 0 lines
+      end
+
+    fun generateLines (index: int): string list =
+      let
+        val line = generateLine index
+      in
+        if line = "" then nil
+        else line :: generateLines (index + 1)
+      end
+  in
+    generateLines 0
+end
+

exercises/practice/transpose/.meta/tests.toml

@@ -0,0 +1,46 @@
+# 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.
+
+[404b7262-c050-4df0-a2a2-0cb06cd6a821]
+description = "empty string"
+
+[a89ce8a3-c940-4703-a688-3ea39412fbcb]
+description = "two characters in a row"
+
+[855bb6ae-4180-457c-abd0-ce489803ce98]
+description = "two characters in a column"
+
+[5ceda1c0-f940-441c-a244-0ced197769c8]
+description = "simple"
+
+[a54675dd-ae7d-4a58-a9c4-0c20e99a7c1f]
+description = "single line"
+
+[0dc2ec0b-549d-4047-aeeb-8029fec8d5c5]
+description = "first line longer than second line"
+
+[984e2ec3-b3d3-4b53-8bd6-96f5ef404102]
+description = "second line longer than first line"
+
+[eccd3784-45f0-4a3f-865a-360cb323d314]
+description = "mixed line length"
+
+[85b96b3f-d00c-4f80-8ca2-c8a5c9216c2d]
+description = "square"
+
+[b9257625-7a53-4748-8863-e08e9d27071d]
+description = "rectangle"
+
+[b80badc9-057e-4543-bd07-ce1296a1ea2c]
+description = "triangle"
+
+[76acfd50-5596-4d05-89f1-5116328a7dd9]
+description = "jagged triangle"