refactor: CountWords (#5428)

* refactor: CountWords

* checkstyle: fix formatting

---------

Co-authored-by: alxkm <alx@alx.com>

src/main/java/com/thealgorithms/others/CountWords.java

@@ -8,17 +8,26 @@ public final class CountWords {
     }
 
     /**
-     * @brief counts the number of words in the input string
+     * Counts the number of words in the input string. Words are defined as sequences of
+     * characters separated by whitespace.
+     *
      * @param s the input string
-     * @return the number of words in the input string
+     * @return the number of words in the input string, or 0 if the string is null or empty
      */
     public static int wordCount(String s) {
         if (s == null || s.isEmpty()) {
             return 0;
         }
-        return s.trim().split("[\\s]+").length;
+        return s.trim().split("\\s+").length;
     }
 
+    /**
+     * Removes all special characters from the input string, leaving only alphanumeric characters
+     * and whitespace.
+     *
+     * @param s the input string
+     * @return a string containing only alphanumeric characters and whitespace
+     */
     private static String removeSpecialCharacters(String s) {
         StringBuilder sb = new StringBuilder();
         for (char c : s.toCharArray()) {
@@ -30,12 +39,12 @@ public final class CountWords {
     }
 
     /**
-     * counts the number of words in a sentence but ignores all potential
-     * non-alphanumeric characters that do not represent a word. runs in O(n)
-     * where n is the length of s
+     * Counts the number of words in a sentence, ignoring all non-alphanumeric characters that do
+     * not contribute to word formation. This method has a time complexity of O(n), where n is the
+     * length of the input string.
      *
-     * @param s String: sentence with word(s)
-     * @return int: number of words
+     * @param s the input string
+     * @return the number of words in the input string, with special characters removed, or 0 if the string is null
      */
     public static int secondaryWordCount(String s) {
         if (s == null) {

src/test/java/com/thealgorithms/others/CountWordsTest.java

@@ -2,36 +2,30 @@ package com.thealgorithms.others;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
-import java.util.HashMap;
-import org.junit.jupiter.api.Test;
+import java.util.stream.Stream;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
 
 class CountWordsTest {
-    @Test
-    public void testWordCount() {
-        HashMap<String, Integer> testCases = new HashMap<>();
-        testCases.put("", 0);
-        testCases.put(null, 0);
-        testCases.put("aaaa bbb cccc", 3);
-        testCases.put("note  extra     spaces   here", 4);
-        testCases.put(" a  b c d  e    ", 5);
 
-        for (final var tc : testCases.entrySet()) {
-            assertEquals(CountWords.wordCount(tc.getKey()), tc.getValue());
-        }
+    @ParameterizedTest
+    @MethodSource("wordCountTestCases")
+    void testWordCount(String input, int expectedCount) {
+        assertEquals(expectedCount, CountWords.wordCount(input));
     }
 
-    @Test
-    public void testSecondaryWordCount() {
-        HashMap<String, Integer> testCases = new HashMap<>();
-        testCases.put("", 0);
-        testCases.put(null, 0);
-        testCases.put("aaaa bbb cccc", 3);
-        testCases.put("this-is-one-word!", 1);
-        testCases.put("What, about, this? Hmmm----strange", 4);
-        testCases.put("word1 word-2 word-3- w?o,r.d.@!@#$&*()<>4", 4);
+    @ParameterizedTest
+    @MethodSource("secondaryWordCountTestCases")
+    void testSecondaryWordCount(String input, int expectedCount) {
+        assertEquals(expectedCount, CountWords.secondaryWordCount(input));
+    }
 
-        for (final var tc : testCases.entrySet()) {
-            assertEquals(CountWords.secondaryWordCount(tc.getKey()), tc.getValue());
-        }
+    private static Stream<Arguments> wordCountTestCases() {
+        return Stream.of(Arguments.of("", 0), Arguments.of(null, 0), Arguments.of("aaaa bbb cccc", 3), Arguments.of("note  extra     spaces   here", 4), Arguments.of(" a  b c d  e    ", 5));
+    }
+
+    private static Stream<Arguments> secondaryWordCountTestCases() {
+        return Stream.of(Arguments.of("", 0), Arguments.of(null, 0), Arguments.of("aaaa bbb cccc", 3), Arguments.of("this-is-one-word!", 1), Arguments.of("What, about, this? Hmmm----strange", 4), Arguments.of("word1 word-2 word-3- w?o,r.d.@!@#$&*()<>4", 4));
     }
 }