Add solution #2845

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,450 LeetCode solutions in JavaScript
+# 1,451 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1425,6 +1425,7 @@
 2799|[Count Complete Subarrays in an Array](./solutions/2799-count-complete-subarrays-in-an-array.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|
+2845|[Count of Interesting Subarrays](./solutions/2845-count-of-interesting-subarrays.js)|Medium|
 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/2845-count-of-interesting-subarrays.js

@@ -0,0 +1,37 @@
+/**
+ * 2845. Count of Interesting Subarrays
+ * https://leetcode.com/problems/count-of-interesting-subarrays/
+ * Difficulty: Medium
+ *
+ * You are given a 0-indexed integer array nums, an integer modulo, and an integer k.
+ *
+ * Your task is to find the count of subarrays that are interesting.
+ *
+ * A subarray nums[l..r] is interesting if the following condition holds:
+ * - Let cnt be the number of indices i in the range [l, r] such that nums[i] % modulo == k.
+ *   Then, cnt % modulo == k.
+ *
+ * Return an integer denoting the count of interesting subarrays.
+ *
+ * Note: A subarray is a contiguous non-empty sequence of elements within an array.
+ */
+
+/**
+ * @param {number[]} nums
+ * @param {number} modulo
+ * @param {number} k
+ * @return {number}
+ */
+var countInterestingSubarrays = function(nums, modulo, k) {
+  const prefixCounts = new Map([[0, 1]]);
+  let currentSum = 0;
+  let result = 0;
+
+  for (const num of nums) {
+    currentSum = (currentSum + (num % modulo === k ? 1 : 0)) % modulo;
+    result += prefixCounts.get((currentSum - k + modulo) % modulo) || 0;
+    prefixCounts.set(currentSum, (prefixCounts.get(currentSum) || 0) + 1);
+  }
+
+  return result;
+};