Add TwoPointerPalindrome.java with test cases and comments

Author: sushma0515

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

@@ -0,0 +1,50 @@
+/**
+ * Check if a given string is a palindrome using the two-pointer technique.
+ * A palindrome is a string that reads the same forward and backward.
+ * 
+ * Example: "level", "madam", "12321" are palindromes.
+ * 
+ * Author: Sushma
+ */
+
+package com.thealgorithms.strings;
+
+public class TwoPointerPalindrome {
+
+    /**
+     * This method checks if the given string is a palindrome using two pointers.
+     *
+     * @param s The input string to check
+     * @return true if the string is a palindrome, false otherwise
+     */
+    public static boolean isPalindrome(String s) {
+
+        // If the string is null or has only 1 or 0 characters, it's a palindrome
+        if (s == null || s.length() <= 1) {
+            return true;
+        }
+
+        // Initialize two pointers: left starting from the beginning,
+        // right starting from the end of the string
+        int left = 0;
+        int right = s.length() - 1;
+
+        // Loop until the two pointers meet in the middle
+        while (left < right) {
+
+            // If characters at left and right don't match, it's not a palindrome
+            if (s.charAt(left) != s.charAt(right)) {
+                return false;
+            }
+
+            // Move the left pointer to the right
+            left++;
+
+            // Move the right pointer to the left
+            right--;
+        }
+
+        // If all characters matched, then it's a palindrome
+        return true;
+    }
+}

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

@@ -0,0 +1,17 @@
+package com.thealgorithms.strings;
+
+import static org.junit.jupiter.api.Assertions.*;
+import org.junit.jupiter.api.Test;
+
+public class TwoPointerPalindromeTest {
+
+    @Test
+    void testPalindrome() {
+        assertTrue(TwoPointerPalindrome.isPalindrome("madam"));
+        assertTrue(TwoPointerPalindrome.isPalindrome("racecar"));
+        assertTrue(TwoPointerPalindrome.isPalindrome("a"));
+
+        assertFalse(TwoPointerPalindrome.isPalindrome("hello"));
+        assertFalse(TwoPointerPalindrome.isPalindrome("world"));
+    }
+}