solve 2843: Count Symmetric Integers in java

Author: anishLearnsToCode

README.md

@@ -852,7 +852,7 @@
 | 2828 | [Check if a String Is an Acronym of Words](https://leetcode.com/problems/check-if-a-string-is-an-acronym-of-words)                                                     |                                                                              [![Java](assets/java.png)](src/CheckIfAStringIsAnAcronymOfWords.java)                                                                               |                                                                                                                                   |
 | 2833 | [Furthest Point From Origin](https://leetcode.com/problems/furthest-point-from-origin)                                                                                 |                                                                                   [![Java](assets/java.png)](src/FurthestPointFromOrigin.java)                                                                                   |                                                                                                                                   |
 | 2839 | [Check if Strings Can be Made Equal With Operations I](https://leetcode.com/problems/check-if-strings-can-be-made-equal-with-operations-i)                             |                                                                         [![Java](assets/java.png)](src/CheckIfStringsCanBeMadeEqualWithOperationsI.java)                                                                         |                                                                                                                                   |
-| 2843 | [Count Symmetric Integers](https://leetcode.com/problems/count-symmetric-integers)                                                                                     |                                                                                                                                                                                                                                  |                                                                                                                                   |
+| 2843 | [Count Symmetric Integers](https://leetcode.com/problems/count-symmetric-integers)                                                                                     |                                                                                   [![Java](assets/java.png)](src/CountSymmetricIntegers.java)                                                                                    |                                                                                                                                   |
 | 2848 | [Points That Intersect With Cars](https://leetcode.com/problems/points-that-intersect-with-cars)                                                                       |                                                                                                                                                                                                                                  |                                                                                                                                   |
 | 2855 | [Minimum Right Shifts to Sort the Array](https://leetcode.com/problems/minimum-right-shifts-to-sort-the-array)                                                         |                                                                                                                                                                                                                                  |                                                                                                                                   |
 | 2859 | [Sum of Values at Indices With K Set Bits](https://leetcode.com/problems/sum-of-values-at-indices-with-k-set-bits)                                                     |                                                                                                                                                                                                                                  |                                                                                                                                   |

src/CountSymmetricIntegers.java

@@ -0,0 +1,33 @@
+// https://leetcode.com/problems/count-symmetric-integers
+// T: O(N)
+// S: O(1)
+
+public class CountSymmetricIntegers {
+    public int countSymmetricIntegers(int low, int high) {
+        int count = 0;
+        for (int start = low ; start <= high ; start++) {
+            final String number = start + "";
+            if (isSymmetric(number)) {
+                count++;
+            }
+        }
+        return count;
+    }
+
+    private static boolean isSymmetric(String number) {
+        if (number.length() % 2 != 0) {
+            return false;
+        }
+        final String firstHalf = number.substring(0, number.length() / 2);
+        final String secondHalf = number.substring(number.length() / 2);
+        return sumOfDigits(firstHalf) == sumOfDigits(secondHalf);
+    }
+
+    private static int sumOfDigits(final String number) {
+        int sum = 0;
+        for (int i = 0 ; i < number.length() ; i++) {
+            sum += number.charAt(i) - '0';
+        }
+        return sum;
+    }
+}