Add one more solution of PalindromeNumber task

Author: andrei-punko

src/main/java/by/andd3dfx/numeric/PalindromeNumber.java

@@ -4,20 +4,56 @@
  * <pre>
  * <a href="https://leetcode.com/problems/palindrome-number/">Task description</a>
  *
- * Given an integer x, return true if x is a palindrome, and false otherwise.
+ * Given an integer x, return true if x is a , and false otherwise.
+ *
+ * Example 1:
+ * Input: x = 121
+ * Output: true
+ * Explanation: 121 reads as 121 from left to right and from right to left.
+ *
+ * Example 2:
+ * Input: x = -121
+ * Output: false
+ * Explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.
+ *
+ * Example 3:
+ * Input: x = 10
+ * Output: false
+ * Explanation: Reads 01 from right to left. Therefore it is not a palindrome.
  * </pre>
  */
 public class PalindromeNumber {
 
     public static boolean isPalindrome(int x) {
+        char[] digits = String.valueOf(x).toCharArray();
+        var n = digits.length;
+        for (int i = 0; i < n / 2; i++) {
+            if (digits[i] != digits[n - i - 1]) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    public static boolean isPalindrome2(int x) {
         if (x < 0) {
             return false;
         }
+        if (x == 0) {
+            return true;
+        }
+        int n = (int) Math.log10(x) + 1;
+        int[] digits = new int[n];
+
+        var curr = 0;
+        while (x > 0) {
+            digits[curr] = x % 10;
+            curr++;
+            x /= 10;
+        }
 
-        var chars = String.valueOf(x).toCharArray();
-        var n = chars.length;
         for (int i = 0; i < n / 2; i++) {
-            if (chars[i] != chars[n - i - 1]) {
+            if (digits[i] != digits[n - i - 1]) {
                 return false;
             }
         }

src/test/java/by/andd3dfx/numeric/PalindromeNumberTest.java

@@ -1,20 +1,32 @@
 package by.andd3dfx.numeric;
 
-import org.junit.Test;
-
 import static by.andd3dfx.numeric.PalindromeNumber.isPalindrome;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import static by.andd3dfx.numeric.PalindromeNumber.isPalindrome2;
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.Test;
 
 public class PalindromeNumberTest {
 
     @Test
     public void testIsPalindrome() {
-        assertTrue(isPalindrome(121));
-        assertTrue(isPalindrome(1568651));
-        assertFalse(isPalindrome(-121));
-        assertFalse(isPalindrome(123));
-        assertFalse(isPalindrome(10));
-        assertTrue(isPalindrome(0));
+        assertThat(isPalindrome(121)).isTrue();
+        assertThat(isPalindrome(1568651)).isTrue();
+        assertThat(isPalindrome(-121)).isFalse();
+        assertThat(isPalindrome(10)).isFalse();
+        assertThat(isPalindrome(123)).isFalse();
+        assertThat(isPalindrome(1001)).isTrue();
+        assertThat(isPalindrome(0)).isTrue();
+    }
+
+    @Test
+    public void testIsPalindrome2() {
+        assertThat(isPalindrome2(121)).isTrue();
+        assertThat(isPalindrome2(1568651)).isTrue();
+        assertThat(isPalindrome2(-121)).isFalse();
+        assertThat(isPalindrome2(10)).isFalse();
+        assertThat(isPalindrome2(123)).isFalse();
+        assertThat(isPalindrome2(1001)).isTrue();
+        assertThat(isPalindrome2(0)).isTrue();
     }
 }