Add PrimeNumberUtils with isPrime and getPrimesUpTo methods

src/main/java/com/thealgorithms/math/PrimeNumberUtils.java

@@ -0,0 +1,49 @@
+package com.thealgorithms.math;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Utility class to work with prime numbers.
+ */
+public class PrimeNumberUtils {
+
+    /**
+     * Checks if a number is a prime.
+     * 
+     * @param n the number to check
+     * @return true if prime, false otherwise
+     */
+    public static boolean isPrime(int n) {
+        if (n <= 1) return false;
+        if (n == 2) return true;
+        if (n % 2 == 0) return false;
+
+        for (int i = 3; i <= Math.sqrt(n); i += 2) {
+            if (n % i == 0) return false;
+        }
+
+        return true;
+    }
+
+    /**
+     * Returns a list of prime numbers up to a given number.
+     * 
+     * @param limit the upper bound (inclusive)
+     * @return list of prime numbers <= limit
+     */
+    public static List<Integer> getPrimesUpTo(int limit) {
+        List<Integer> primes = new ArrayList<>();
+        for (int i = 2; i <= limit; i++) {
+            if (isPrime(i)) {
+                primes.add(i);
+            }
+        }
+        return primes;
+    }
+
+    public static void main(String[] args) {
+        System.out.println("Is 17 prime? " + isPrime(17));
+        System.out.println("Primes up to 30: " + getPrimesUpTo(30));
+    }
+}

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

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+package com.thealgorithms.others;
+
+public class EvenOddChecker {
+    public static String checkEvenOdd(int number) {
+        return number % 2 == 0 ? "Even" : "Odd";
+    }
+
+    public static void main(String[] args) {
+        int test = 7;
+        System.out.println(test + " is " + checkEvenOdd(test));
+    }
+}

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

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+package com.thealgorithms.strings;
+
+/**
+ * Utility class to check if a string is a palindrome.
+ */
+public class PalindromeChecker {
+
+    /**
+     * Checks if the given input is a palindrome.
+     * Ignores spaces, punctuation, and case.
+     *
+     * @param input the string to check
+     * @return true if it's a palindrome, false otherwise
+     */
+    public static boolean isPalindrome(String input) {
+        if (input == null) {
+            return false;
+        }
+        // Remove non-letter characters and convert to lowercase
+        String cleaned = input.replaceAll("[^a-zA-Z]", "").toLowerCase();
+        int left = 0;
+        int right = cleaned.length() - 1;
+
+        while (left < right) {
+            if (cleaned.charAt(left) != cleaned.charAt(right)) {
+                return false;
+            }
+            left++;
+            right--;
+        }
+
+        return true;
+    }
+
+    public static void main(String[] args) {
+        String test1 = "A man a plan a canal Panama";
+        String test2 = "OpenAI";
+        System.out.println("\"" + test1 + "\" is palindrome? " + isPalindrome(test1));
+        System.out.println("\"" + test2 + "\" is palindrome? " + isPalindrome(test2));
+    }
+}