Add transpose exercise (#508)

Author: keiravillekode

config.json

@@ -1003,6 +1003,14 @@
         "prerequisites": [],
         "difficulty": 5
       },
+      {
+        "slug": "transpose",
+        "name": "Transpose",
+        "uuid": "3cad82e8-b201-4f4c-81eb-8239521be255",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
+      },
       {
         "slug": "variable-length-quantity",
         "name": "Variable Length Quantity",

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.zig"
+    ],
+    "test": [
+      "test_transpose.zig"
+    ],
+    "example": [
+      ".meta/example.zig"
+    ]
+  },
+  "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.zig

@@ -0,0 +1,37 @@
+const std = @import("std");
+const mem = std.mem;
+
+fn free(allocator: mem.Allocator, array_list: *std.ArrayList([]u8)) void {
+    for (array_list.items) |item| {
+        allocator.free(item);
+    }
+    array_list.deinit(allocator);
+}
+
+pub fn transpose(allocator: mem.Allocator, lines: []const []const u8) mem.Allocator.Error![][]u8 {
+    var longest: usize = 0;
+    for (lines) |line| {
+        if (longest < line.len) {
+            longest = line.len;
+        }
+    }
+
+    var array_list = try std.ArrayList([]u8).initCapacity(allocator, longest);
+    errdefer free(allocator, &array_list);
+    for (0..longest) |i| {
+        var line = try std.ArrayList(u8).initCapacity(allocator, lines.len);
+        defer line.deinit(allocator);
+        for (0..lines.len) |j| {
+            if (lines[j].len <= i) {
+                continue;
+            }
+
+            while (line.items.len < j) {
+                line.appendAssumeCapacity(' ');
+            }
+            line.appendAssumeCapacity(lines[j][i]);
+        }
+        array_list.appendAssumeCapacity(try line.toOwnedSlice(allocator));
+    }
+    return array_list.toOwnedSlice(allocator);
+}

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"