Add transpose exercise (#520)

Author: keiravillekode

config.json

@@ -652,6 +652,14 @@
         "prerequisites": [],
         "difficulty": 4
       },
+      {
+        "slug": "transpose",
+        "name": "Transpose",
+        "uuid": "486e4c05-1741-4b33-8191-86bd3f50149d",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 4
+      },
       {
         "slug": "twelve-days",
         "name": "Twelve Days",

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.el"
+    ],
+    "test": [
+      "transpose-test.el"
+    ],
+    "example": [
+      ".meta/example.el"
+    ]
+  },
+  "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.el

@@ -0,0 +1,33 @@
+;;; transpose.el --- Transpose (exercism)  -*- lexical-binding: t; -*-
+
+;;; Commentary:
+
+;;; Code:
+
+(require 'cl-lib)
+
+(defun column (col reversed height)
+  (cond ((null reversed) "")
+        ((<= (length (car reversed)) col) (column col (cdr reversed) (1- height)))
+        (t (let ((word (make-string height ?\s)))
+             (cl-loop
+               for row from (1- height) downto 0
+               for line = (car reversed)
+
+               when (< col (length line))
+               do (aset word row (aref line col))
+
+               do (setq reversed (cdr reversed)))
+             word))))
+
+(defun transpose (lines)
+  (when lines
+    (let ((height (length lines))
+          (width (apply #'max (mapcar #'length lines)))
+          (reversed (reverse lines)))
+      (cl-loop for col from 0 below width
+        collect (column col reversed height)))))
+
+(provide 'transpose)
+;;; transpose.el ends here
+

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"

exercises/practice/transpose/transpose-test.el

@@ -0,0 +1,178 @@
+;;; transpose-test.el --- Tests for Transpose (exercism)  -*- lexical-binding: t; -*-
+
+;;; Commentary:
+
+;;; Code:
+
+
+(load-file "transpose.el")
+(declare-function transpose "transpose.el" (lines))
+
+
+(ert-deftest empty-string ()
+  (let ((expected '()))
+    (should (equal (transpose '()) expected))))
+
+
+(ert-deftest two-characters-in-a-row ()
+  (let ((expected '("A"
+                    "1")))
+    (should (equal (transpose '("A1")) expected))))
+
+
+(ert-deftest two-characters-in-a-column ()
+  (let ((expected '("A1")))
+    (should (equal (transpose '("A"
+                                "1")) expected))))
+
+
+(ert-deftest simple ()
+  (let ((expected '("A1"
+                    "B2"
+                    "C3")))
+    (should (equal (transpose '("ABC"
+                                "123")) expected))))
+
+
+(ert-deftest single-line ()
+  (let ((expected '("S"
+                    "i"
+                    "n"
+                    "g"
+                    "l"
+                    "e"
+                    " "
+                    "l"
+                    "i"
+                    "n"
+                    "e"
+                    ".")))
+    (should (equal (transpose '("Single line.")) expected))))
+
+
+(ert-deftest first-line-longer-than-second-line ()
+  (let ((expected '("TT"
+                    "hh"
+                    "ee"
+                    "  "
+                    "ff"
+                    "oi"
+                    "uf"
+                    "rt"
+                    "th"
+                    "h "
+                    " l"
+                    "li"
+                    "in"
+                    "ne"
+                    "e."
+                    ".")))
+    (should (equal (transpose '("The fourth line."
+                                "The fifth line.")) expected))))
+
+
+(ert-deftest second-line-longer-than-first-line ()
+  (let ((expected '("TT"
+                    "hh"
+                    "ee"
+                    "  "
+                    "fs"
+                    "ie"
+                    "rc"
+                    "so"
+                    "tn"
+                    " d"
+                    "l "
+                    "il"
+                    "ni"
+                    "en"
+                    ".e"
+                    " .")))
+    (should (equal (transpose '("The first line."
+                                "The second line.")) expected))))
+
+
+(ert-deftest mixed-line-length ()
+  (let ((expected '("TAAA"
+                    "h   "
+                    "elll"
+                    " ooi"
+                    "lnnn"
+                    "ogge"
+                    "n e."
+                    "glr"
+                    "ei "
+                    "snl"
+                    "tei"
+                    " .n"
+                    "l e"
+                    "i ."
+                    "n"
+                    "e"
+                    ".")))
+    (should (equal (transpose '("The longest line."
+                                "A long line."
+                                "A longer line."
+                                "A line.")) expected))))
+
+
+(ert-deftest square ()
+  (let ((expected '("HEART"
+                    "EMBER"
+                    "ABUSE"
+                    "RESIN"
+                    "TREND")))
+    (should (equal (transpose '("HEART"
+                                "EMBER"
+                                "ABUSE"
+                                "RESIN"
+                                "TREND")) expected))))
+
+
+(ert-deftest rectangle ()
+  (let ((expected '("FOBS"
+                    "RULE"
+                    "ATOP"
+                    "CLOT"
+                    "TIME"
+                    "UNIT"
+                    "RENT"
+                    "EDGE")))
+    (should (equal (transpose '("FRACTURE"
+                                "OUTLINED"
+                                "BLOOMING"
+                                "SEPTETTE")) expected))))
+
+
+(ert-deftest triangle ()
+  (let ((expected '("TEASER"
+                    " EASER"
+                    "  ASER"
+                    "   SER"
+                    "    ER"
+                    "     R")))
+    (should (equal (transpose '("T"
+                                "EE"
+                                "AAA"
+                                "SSSS"
+                                "EEEEE"
+                                "RRRRRR")) expected))))
+
+
+(ert-deftest jagged-triangle ()
+  (let ((expected '("123456"
+                    "1 3456"
+                    "  3456"
+                    "  3 56"
+                    "    56"
+                    "    5")))
+    (should (equal (transpose '("11"
+                                "2"
+                                "3333"
+                                "444"
+                                "555555"
+                                "66666")) expected))))
+
+
+(provide 'transpose-test)
+;;; transpose-test.el ends here

exercises/practice/transpose/transpose.el

@@ -0,0 +1,14 @@
+;;; transpose.el --- Transpose (exercism)  -*- lexical-binding: t; -*-
+
+;;; Commentary:
+
+;;; Code:
+
+
+(defun transpose (lines)
+  (error "Delete this S-Expression and write your own implementation"))
+
+
+(provide 'transpose)
+;;; transpose.el ends here
+