Revert "refactor: Enhance docs, code, add tests in HappyNumbersSeq"

This reverts commit 9e8afb4.

Author: Hardvan

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

@@ -5,52 +5,12 @@
 import java.util.Scanner;
 import java.util.Set;
 
-/**
- * A utility class for working with Happy Numbers.
- *
- * <p>
- * A Happy Number is defined by the following process:
- * Starting with any positive integer, replace the number by the sum of the
- * squares of its digits.
- * Repeat the process until the number equals 1 (where it will stay), or it
- * loops endlessly in a
- * cycle which does not include 1.
- * Those numbers for which this process ends in 1 are happy numbers, while those
- * that do not end
- * in 1 are unhappy (or sad) numbers.
- *
- * <p>
- * For example:
- * <ul>
- * <li>7 is a happy number: 7 → 49 → 97 → 130 → 10 → 1</li>
- * <li>2 is not a happy number (sad number): 2 → 4 → 16 → 37 → 58 → 89 → 145 →
- * 42 → 20 → 4 (cycle)</li>
- * </ul>
- *
- * @see <a href="https://en.wikipedia.org/wiki/Happy_number">Happy Number -
- *      Wikipedia</a>
- * @see <a href="https://mathworld.wolfram.com/HappyNumber.html">Happy Number -
- *      Wolfram MathWorld</a>
- */
 public final class HappyNumbersSeq {
     private HappyNumbersSeq() {
     }
 
-    /**
-     * Known cycle numbers that indicate a sad number.
-     * If the sequence reaches any of these numbers, it will cycle indefinitely
-     * without reaching 1.
-     */
     private static final Set<Integer> CYCLE_NUMS = new HashSet<>(Arrays.asList(4, 16, 20, 37, 58, 145));
 
-    /**
-     * Main method to demonstrate happy number detection.
-     * Reads a number from user input and displays the sequence until it reaches 1
-     * (happy)
-     * or enters a cycle (sad).
-     *
-     * @param args command-line arguments (not used)
-     */
     public static void main(String[] args) {
         Scanner in = new Scanner(System.in);
         System.out.print("Enter number: ");
@@ -64,47 +24,16 @@ public static void main(String[] args) {
         in.close();
     }
 
-    /**
-     * Determines if a number is a happy number.
-     *
-     * @param n the number to check (must be positive)
-     * @return {@code true} if the number is happy, {@code false} otherwise
-     * @throws IllegalArgumentException if n is not positive
-     */
-    public static boolean isHappy(int n) {
-        if (n <= 0) {
-            throw new IllegalArgumentException("Number must be positive");
+    private static int sumSquares(int n) {
+        int s = 0;
+        for (; n > 0; n /= 10) {
+            int r = n % 10;
+            s += r * r;
         }
-        while (n != 1 && !isSad(n)) {
-            n = sumSquares(n);
-        }
-        return n == 1;
-    }
-
-    /**
-     * Computes the sum of the squares of the digits of a number.
-     *
-     * @param n the number whose digits will be squared and summed
-     * @return the sum of the squares of the digits
-     */
-    static int sumSquares(int n) {
-        int sum = 0;
-        while (n > 0) {
-            int digit = n % 10;
-            sum += digit * digit;
-            n /= 10;
-        }
-        return sum;
+        return s;
     }
 
-    /**
-     * Checks if a number is part of the known cycle that indicates a sad number.
-     *
-     * @param n the number to check
-     * @return {@code true} if the number is in the sad cycle, {@code false}
-     *         otherwise
-     */
-    static boolean isSad(int n) {
+    private static boolean isSad(int n) {
         return CYCLE_NUMS.contains(n);
     }
 }