refactor: adding docs for LongestCommonPrefixTest and Parameterized Tests (#6360)

* refactor: adding docs for LongestCommonPrefixTest and Parameterized Tests

* checkstyle: fix clang formatting

---------

Co-authored-by: Deniz Altunkapan <93663085+DenizAltunkapan@users.noreply.github.com>

src/main/java/com/thealgorithms/strings/LongestCommonPrefix.java

@@ -2,21 +2,41 @@ package com.thealgorithms.strings;
 
 import java.util.Arrays;
 
+/**
+ * Utility class for string operations.
+ * <p>
+ * This class provides a method to find the longest common prefix (LCP)
+ * among an array of strings.
+ * </p>
+ *
+ * @see <a href="https://en.wikipedia.org/wiki/Longest_common_prefix">Longest Common Prefix - Wikipedia</a>
+ */
 public final class LongestCommonPrefix {
-    public String longestCommonPrefix(String[] strs) {
+
+    private LongestCommonPrefix() {
+    }
+
+    /**
+     * Finds the longest common prefix among a list of strings using lexicographical sorting.
+     * The prefix is common to the first and last elements after sorting the array.
+     *
+     * @param strs array of input strings
+     * @return the longest common prefix, or empty string if none exists
+     */
+    public static String longestCommonPrefix(String[] strs) {
         if (strs == null || strs.length == 0) {
             return "";
         }
 
         Arrays.sort(strs);
-        String shortest = strs[0];
-        String longest = strs[strs.length - 1];
+        String first = strs[0];
+        String last = strs[strs.length - 1];
 
         int index = 0;
-        while (index < shortest.length() && index < longest.length() && shortest.charAt(index) == longest.charAt(index)) {
+        while (index < first.length() && index < last.length() && first.charAt(index) == last.charAt(index)) {
             index++;
         }
 
-        return shortest.substring(0, index);
+        return first.substring(0, index);
     }
 }