feat: kata/ticker

kata/6-kyu/index.md

@@ -404,6 +404,7 @@
 - [The Walker](the-walker "5b40b666dfb4291ad9000049")
 - [Throw without throwing](throw-without-throwing "5943db60800cebe12000003d")
 - [Tic-Tac-Toe-like table Generator](tic-tac-toe-like-table-generator "5b817c2a0ce070ace8002be0")
+- [Ticker](ticker "5a959662373c2e761d000183")
 - [Time Math](time-math "5aceae374d9fd1266f0000f0")
 - [Tortoise racing](tortoise-racing "55e2adece53b4cdcb900006c")
 - [Traffic Lights - one car](traffic-lights-one-car "5d0ae91acac0a50232e8a547")

kata/6-kyu/ticker/README.md

@@ -0,0 +1,29 @@
+# [Ticker](https://www.codewars.com/kata/ticker "https://www.codewars.com/kata/5a959662373c2e761d000183")
+
+While using public transport we could see simple displays with a ticker. It often provides information about next stations and expected
+arrival time.
+
+Let's implement a function which will return a chunk of text to be displayed on a display of fixed width.
+The function should take `text` to display, `width` of the display and `tick` as a step of the ticker. The function will be called many
+times with `tick` parameter constantly incrementing.
+
+At very beginning the display is empty. At first step only one character should be displayed in the most right position and so on. When the
+message is displayed, it should disappear char by char to left position and return to blank state of the display. After that cycle should
+start again.
+
+For example
+
+```java
+ticker("Hello world!", 10, 4); // " Hell"
+```
+
+We could expect that our function will be called from simple script like this one
+
+```java
+void demo(String text, int width) {
+  for (int tick = 0; isRunning(); tick++) {
+    display.setText(ticker(text, width, tick));
+    Thread.sleep(100L);
+  }
+}
+```

kata/6-kyu/ticker/main/Kata.java

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+interface Kata {
+  static String ticker(String text, int width, int tick) {
+    tick %= (width + text.length());
+    return (" ".repeat(width) + text + " ".repeat(width)).substring(tick, tick + width);
+  }
+}

kata/6-kyu/ticker/test/SolutionTest.java

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+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 = """
+      10, 0, '          '
+      10, 5, '     Beaut'
+      10, 30, 'than ugly.'
+      10, 39, '.         '
+      10, 41, '         B'
+      """)
+  void sample(int width, int tick, String display) {
+    assertEquals(display, Kata.ticker("Beautiful is better than ugly.", width, tick));
+  }
+}