feat: kata/stones-on-the-table (#872)

* docs: kata description

* feat: kata/stones-on-the-table

---------

Co-authored-by: ParanoidUser <[email protected]>

Author: github-actions[bot]

kata/7-kyu/index.md

@@ -531,6 +531,7 @@
 - [Status Arrays](status-arrays "601c18c1d92283000ec86f2b")
 - [Steps](steps-1 "6473603854720900496e1c82")
 - [Stone Pickaxe Crafting](stone-pickaxe-crafting "65c0161a2380ae78052e5731")
+- [Stones on the Table](stones-on-the-table "5f70e4cce10f9e0001c8995a")
 - [Strange mathematics](strange-mathematics "604517d65b464d000d51381f")
 - [String ends with?](string-ends-with "51f2d1cafc9c0f745c00037d")
 - [String interlacing](string-interlacing "56e120ee2bb224eaa3000ba2")

kata/7-kyu/stones-on-the-table/README.md

@@ -0,0 +1,14 @@
+# [Stones on the Table](https://www.codewars.com/kata/stones-on-the-table "https://www.codewars.com/kata/5f70e4cce10f9e0001c8995a")
+
+There are some stones on Bob's table in a row, and each of them can be red, green or blue, indicated by the characters `R`, `G`, and `B`.
+
+Help Bob find the minimum number of stones he needs to remove from the table so that the stones in each pair of adjacent stones have
+different colors.
+
+Examples:
+
+```
+"RGBRGBRGGB" => 1
+"RGGRGBBRGRR" => 3
+"RRRRGGGGBBBB" => 9
+```

kata/7-kyu/stones-on-the-table/main/Solution.java

@@ -0,0 +1,5 @@
+interface Solution {
+  static int solve(String stones) {
+    return stones.length() - stones.replaceAll("(.)\\1+", "$1").length();
+  }
+}

kata/7-kyu/stones-on-the-table/test/SolutionTest.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 SolutionTest {
+  @ParameterizedTest
+  @CsvSource(textBlock = """
+      RGBRGB, 0
+      RRGGBB, 3
+      BGRBBGGBRRR, 4
+      GBBBGGRRGRB, 4
+      GBRGGRBBBBRRGGGB, 7
+      """)
+  void sample(String stones, int duplicates) {
+    assertEquals(duplicates, Solution.solve(stones));
+  }
+}