kata/count-the-ones

Author: ParanoidUser

kata/7-kyu/count-the-ones/README.md

@@ -1,16 +1,12 @@
 # [Count the Ones](https://www.codewars.com/kata/count-the-ones "https://www.codewars.com/kata/5519e930cd82ff8a9a000216")
 
-The __Hamming weight__ of a string is the number of symbols that are different from the zero-symbol of the alphabet used. There are several algorithms for efficient computing of the Hamming weight for numbers. In this Kata, speaking technically, you have to find out the number of '1' bits in a binary representation of a number. Thus,
+The __Hamming weight__ of a string is the number of symbols that are different from the zero-symbol of the alphabet used. There are several
+algorithms for efficient computing of the Hamming weight for numbers. In this Kata, speaking technically, you have to find out the number
+of '1' bits in a binary representation of a number. Thus,
 
-```ruby
-hamming_weight(10) # 1010 => 2
-hamming_weight(21) # 10101 => 3
 ```
-```javascript
 hammingWeight(10) // 1010 => 2
 hammingWeight(21) // 10101 => 3
 ```
 
-The interesting part of this task is that you have to do it *without* string operation (hey, it's not really interesting otherwise)
-
- ;)
+The interesting part of this task is that you have to do it *without* string operation (hey, it's not really interesting otherwise)

kata/7-kyu/count-the-ones/main/HammingWeight.java

@@ -0,0 +1,5 @@
+interface HammingWeight {
+  static int hammingWeight(int i) {
+    return Integer.bitCount(i);
+  }
+}

kata/7-kyu/count-the-ones/test/SolutionTest.java

@@ -0,0 +1,15 @@
+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, 2
+      21, 3
+      """)
+  void sample(int n, int expected) {
+    assertEquals(expected, HammingWeight.hammingWeight(n));
+  }
+}