feat: kata/numbers-to-letters (#798)

* docs: kata description

* feat: kata/numbers-to-letters

---------

Co-authored-by: ParanoidUser <5120290+ParanoidUser@users.noreply.github.com>

Author: github-actions[bot]

kata/7-kyu/index.md

@@ -366,6 +366,7 @@
 - [Number-Star ladder](number-star-ladder "5631213916d70a0979000066")
 - [Number to digit tiers](number-to-digit-tiers "586bca7fa44cfc833e00005c")
 - [Numbers in strings](numbers-in-strings "59dd2c38f703c4ae5e000014")
+- [Numbers to Letters](numbers-to-letters "57ebaa8f7b45ef590c00000c")
 - [Numbers Which Sum of Powers of Its Digits Is The Same Number](numbers-which-sum-of-powers-of-its-digits-is-the-same-number "560a4962c0cc5c2a16000068")
 - [Numbers with d occurrences of digit d](numbers-with-d-occurences-of-digit-d "5a40fc7ce1ce0e34440000a3")
 - [Numbers with this digit inside](numbers-with-this-digit-inside "57ad85bb7cb1f3ae7c000039")

kata/7-kyu/numbers-to-letters/README.md

@@ -0,0 +1,6 @@
+# [Numbers to Letters](https://www.codewars.com/kata/numbers-to-letters "https://www.codewars.com/kata/57ebaa8f7b45ef590c00000c")
+
+Given an array of numbers (in string format), you must return a string. The numbers correspond to the letters of the alphabet in reverse
+order: a=26, z=1 etc. You should also account for `'!'`, `'?'` and `' '` that are represented by '27', '28' and '29' respectively.
+
+All inputs will be valid.

kata/7-kyu/numbers-to-letters/main/Kata.java

@@ -0,0 +1,8 @@
+import static java.util.stream.Stream.of;
+import static java.util.stream.Collectors.joining;
+
+interface Kata{
+  static String switcher(String[] arr){
+    return of(arr).map(n -> "_zyxwvutsrqponmlkjihgfedcba!? ".charAt(Integer.parseInt(n)) + "").collect(joining());
+  }
+}

kata/7-kyu/numbers-to-letters/test/SwitcherTest.java

@@ -0,0 +1,18 @@
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+
+class SwitcherTest {
+  @ParameterizedTest
+  @CsvSource(delimiter = '|', textBlock = """
+      12 | o
+      4,24 | wc
+      24,12,23,22,4,26,9,8 | codewars
+      25,7,8,4,14,23,8,25,23,29,16,16,4 | btswmdsbd kkw
+      12,28,25,21,25,7,11,22,15 | o?bfbtpel
+      """)
+  void sample(String arr, String expected) {
+    assertEquals(expected, Kata.switcher(arr.split(",")));
+  }
+}