feat: kata/perimeter-sequence (#790)

* docs: kata description

* feat: kata/perimeter-sequence

---------

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

Author: github-actions[bot]

kata/7-kyu/index.md

@@ -387,6 +387,7 @@
 - [Password maker](password-maker "5637b03c6be7e01d99000046")
 - [Password System](password-system "57a23e3753ba332b8e0008da")
 - [Paul's Misery](pauls-misery "57ee31c5e77282c24d000024")
+- [Perimeter sequence](perimeter-sequence "589519d1f0902e01af000054")
 - [Perpendicular lines](perpendicular-lines-1 "6391fe3f322221003db3bad6")
 - [Pizza Payments](pizza-payments "5b043e3886d0752685000009")
 - [Plan Your Dream Wedding](plan-your-dream-wedding "66314d6b7cb7030393dddf8a")

kata/7-kyu/perimeter-sequence/README.md

@@ -0,0 +1,9 @@
+# [Perimeter sequence](https://www.codewars.com/kata/perimeter-sequence "https://www.codewars.com/kata/589519d1f0902e01af000054")
+
+The first three stages of a sequence are shown.
+
+![blocks](https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTVw-YEuGbD31EB47C7PSi_RpBxr5EJSydV9dj5lOmzsDWFsoAs)
+
+The block size is `a` by `a` and `a ≥ 1`.
+
+What is the perimeter of the `n`th shape in the sequence (`n ≥ 1`) ?

kata/7-kyu/perimeter-sequence/main/Kata.java

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+interface Kata{
+  static int perimeterSequence(int a, int n){
+    return 4 * a * n;
+  }
+}

kata/7-kyu/perimeter-sequence/test/PerimeterSequenceTest.java

@@ -0,0 +1,16 @@
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+
+class PerimeterSequenceTest {
+  @ParameterizedTest
+  @CsvSource(textBlock = """
+      1, 1, 4
+      1, 2, 8
+      1, 3, 12
+      """)
+  void sample(int a, int n, int p) {
+    assertEquals(p, Kata.perimeterSequence(a, n));
+  }
+}