Add solution #2843

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,240 LeetCode solutions in JavaScript
+# 1,241 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1216,6 +1216,7 @@
 2727|[Is Object Empty](./solutions/2727-is-object-empty.js)|Easy|
 2780|[Minimum Index of a Valid Split](./solutions/2780-minimum-index-of-a-valid-split.js)|Medium|
 2818|[Apply Operations to Maximize Score](./solutions/2818-apply-operations-to-maximize-score.js)|Hard|
+2843|[Count Symmetric Integers](./solutions/2843-count-symmetric-integers.js)|Easy|
 2873|[Maximum Value of an Ordered Triplet I](./solutions/2873-maximum-value-of-an-ordered-triplet-i.js)|Easy|
 2874|[Maximum Value of an Ordered Triplet II](./solutions/2874-maximum-value-of-an-ordered-triplet-ii.js)|Medium|
 2948|[Make Lexicographically Smallest Array by Swapping Elements](./solutions/2948-make-lexicographically-smallest-array-by-swapping-elements.js)|Medium|

solutions/2843-count-symmetric-integers.js

@@ -0,0 +1,39 @@
+/**
+ * 2843. Count Symmetric Integers
+ * https://leetcode.com/problems/count-symmetric-integers/
+ * Difficulty: Easy
+ *
+ * You are given two positive integers low and high.
+ *
+ * An integer x consisting of 2 * n digits is symmetric if the sum of the first n digits of x is
+ * equal to the sum of the last n digits of x. Numbers with an odd number of digits are never
+ * symmetric.
+ *
+ * Return the number of symmetric integers in the range [low, high].
+ */
+
+/**
+ * @param {number} low
+ * @param {number} high
+ * @return {number}
+ */
+var countSymmetricIntegers = function(low, high) {
+  let result = 0;
+
+  for (let number = low; number <= high; number++) {
+    if (isSymmetric(number)) result++;
+  }
+
+  return result;
+
+  function isSymmetric(number) {
+    const digits = number.toString().split('');
+    const length = digits.length;
+    if (length % 2 !== 0) return false;
+    const mid = length / 2;
+    const firstHalfSum = digits.slice(0, mid).reduce((sum, digit) => sum + Number(digit), 0);
+    const secondHalfSum = digits.slice(mid).reduce((sum, digit) => sum + Number(digit), 0);
+
+    return firstHalfSum === secondHalfSum;
+  }
+};