Add series exercise

Author: keiravillekode

config.json

@@ -1027,6 +1027,14 @@
         "prerequisites": [],
         "difficulty": 5
       },
+      {
+        "slug": "series",
+        "name": "Series",
+        "uuid": "fc7d90fa-0bb6-4560-8dee-ddf82adf412c",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
+      },
       {
         "slug": "spiral-matrix",
         "name": "Spiral Matrix",

exercises/practice/series/.docs/instructions.md

@@ -0,0 +1,19 @@
+# Instructions
+
+Given a string of digits, output all the contiguous substrings of length `n` in that string in the order that they appear.
+
+For example, the string "49142" has the following 3-digit series:
+
+- "491"
+- "914"
+- "142"
+
+And the following 4-digit series:
+
+- "4914"
+- "9142"
+
+And if you ask for a 6-digit series from a 5-digit string, you deserve whatever you get.
+
+Note that these series are only required to occupy _adjacent positions_ in the input;
+the digits need not be _numerically consecutive_.

exercises/practice/series/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "keiravillekode"
+  ],
+  "files": {
+    "solution": [
+      "series.zig"
+    ],
+    "test": [
+      "test_series.zig"
+    ],
+    "example": [
+      ".meta/example.zig"
+    ]
+  },
+  "blurb": "Given a string of digits, output all the contiguous substrings of length `n` in that string.",
+  "source": "A subset of the Problem 8 at Project Euler",
+  "source_url": "https://projecteuler.net/problem=8"
+}

exercises/practice/series/.meta/example.zig

@@ -0,0 +1,25 @@
+const std = @import("std");
+const fmt = std.fmt;
+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 slices(comptime slice_length: usize, allocator: mem.Allocator, series: []const u8) mem.Allocator.Error![][]u8 {
+    comptime {
+        std.debug.assert(slice_length > 0);
+    }
+
+    var array_list = std.ArrayList([]u8).empty;
+    errdefer free(allocator, &array_list);
+    if (slice_length <= series.len) {
+        for (slice_length..(series.len + 1)) |i| {
+            try array_list.append(allocator, try fmt.allocPrint(allocator, "{s}", .{series[(i - slice_length)..i]}));
+        }
+    }
+    return array_list.toOwnedSlice(allocator);
+}

exercises/practice/series/.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.
+
+[7ae7a46a-d992-4c2a-9c15-a112d125ebad]
+description = "slices of one from one"
+
+[3143b71d-f6a5-4221-aeae-619f906244d2]
+description = "slices of one from two"
+
+[dbb68ff5-76c5-4ccd-895a-93dbec6d5805]
+description = "slices of two"
+
+[19bbea47-c987-4e11-a7d1-e103442adf86]
+description = "slices of two overlap"
+
+[8e17148d-ba0a-4007-a07f-d7f87015d84c]
+description = "slices can include duplicates"
+
+[bd5b085e-f612-4f81-97a8-6314258278b0]
+description = "slices of a long series"
+
+[6d235d85-46cf-4fae-9955-14b6efef27cd]
+description = "slice length is too large"
+
+[d7957455-346d-4e47-8e4b-87ed1564c6d7]
+description = "slice length is way too large"
+
+[d34004ad-8765-4c09-8ba1-ada8ce776806]
+description = "slice length cannot be zero"
+include = false
+
+[10ab822d-8410-470a-a85d-23fbeb549e54]
+description = "slice length cannot be negative"
+include = false
+
+[c7ed0812-0e4b-4bf3-99c4-28cbbfc246a2]
+description = "empty series is invalid"
+include = false

exercises/practice/series/series.zig

@@ -0,0 +1,12 @@
+const std = @import("std");
+const mem = std.mem;
+
+pub fn slices(comptime slice_length: usize, allocator: mem.Allocator, series: []const u8) mem.Allocator.Error![][slice_length]u8 {
+    comptime {
+        std.debug.assert(slice_length > 0);
+    }
+
+    _ = allocator;
+    _ = series;
+    @compileError("please implement the slices function");
+}

exercises/practice/series/test_series.zig

@@ -0,0 +1,99 @@
+const std = @import("std");
+const testing = std.testing;
+
+const slices = @import("series.zig").slices;
+
+fn free(arr: [][]u8) void {
+    for (arr) |s| {
+        testing.allocator.free(s);
+    }
+    testing.allocator.free(arr);
+}
+
+test "slices of one from one" {
+    const series = "1";
+    const expected = [_][]const u8{"1"};
+    const actual = try slices(1, testing.allocator, series);
+    defer free(actual);
+    try testing.expectEqual(expected.len, actual.len);
+    for (expected, 0..) |expected_slice, i| {
+        try testing.expectEqualStrings(expected_slice, actual[i]);
+    }
+}
+
+test "slices of one from two" {
+    const series = "12";
+    const expected = [_][]const u8{ "1", "2" };
+    const actual = try slices(1, testing.allocator, series);
+    defer free(actual);
+    try testing.expectEqual(expected.len, actual.len);
+    for (expected, 0..) |expected_slice, i| {
+        try testing.expectEqualStrings(expected_slice, actual[i]);
+    }
+}
+
+test "slices of two" {
+    const series = "35";
+    const expected = [_][]const u8{"35"};
+    const actual = try slices(2, testing.allocator, series);
+    defer free(actual);
+    try testing.expectEqual(expected.len, actual.len);
+    for (expected, 0..) |expected_slice, i| {
+        try testing.expectEqualStrings(expected_slice, actual[i]);
+    }
+}
+
+test "slices of two overlap" {
+    const series = "9142";
+    const expected = [_][]const u8{ "91", "14", "42" };
+    const actual = try slices(2, testing.allocator, series);
+    defer free(actual);
+    try testing.expectEqual(expected.len, actual.len);
+    for (expected, 0..) |expected_slice, i| {
+        try testing.expectEqualStrings(expected_slice, actual[i]);
+    }
+}
+
+test "slices can include duplicates" {
+    const series = "777777";
+    const expected = [_][]const u8{ "777", "777", "777", "777" };
+    const actual = try slices(3, testing.allocator, series);
+    defer free(actual);
+    try testing.expectEqual(expected.len, actual.len);
+    for (expected, 0..) |expected_slice, i| {
+        try testing.expectEqualStrings(expected_slice, actual[i]);
+    }
+}
+
+test "slices of a long series" {
+    const series = "918493904243";
+    const expected = [_][]const u8{ "91849", "18493", "84939", "49390", "93904", "39042", "90424", "04243" };
+    const actual = try slices(5, testing.allocator, series);
+    defer free(actual);
+    try testing.expectEqual(expected.len, actual.len);
+    for (expected, 0..) |expected_slice, i| {
+        try testing.expectEqualStrings(expected_slice, actual[i]);
+    }
+}
+
+test "slice length is too large" {
+    const series = "12345";
+    const expected = [_][]const u8{};
+    const actual = try slices(6, testing.allocator, series);
+    defer free(actual);
+    try testing.expectEqual(expected.len, actual.len);
+    for (expected, 0..) |expected_slice, i| {
+        try testing.expectEqualStrings(expected_slice, actual[i]);
+    }
+}
+
+test "slice length is way too large" {
+    const series = "12345";
+    const expected = [_][]const u8{};
+    const actual = try slices(42, testing.allocator, series);
+    defer free(actual);
+    try testing.expectEqual(expected.len, actual.len);
+    for (expected, 0..) |expected_slice, i| {
+        try testing.expectEqualStrings(expected_slice, actual[i]);
+    }
+}