Add solution #2176

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,335 LeetCode solutions in JavaScript
+# 1,336 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1222,6 +1222,7 @@
 2140|[Solving Questions With Brainpower](./solutions/2140-solving-questions-with-brainpower.js)|Medium|
 2154|[Keep Multiplying Found Values by Two](./solutions/2154-keep-multiplying-found-values-by-two.js)|Easy|
 2161|[Partition Array According to Given Pivot](./solutions/2161-partition-array-according-to-given-pivot.js)|Medium|
+2176|[Count Equal and Divisible Pairs in an Array](./solutions/2176-count-equal-and-divisible-pairs-in-an-array.js)|Easy|
 2179|[Count Good Triplets in an Array](./solutions/2179-count-good-triplets-in-an-array.js)|Hard|
 2185|[Counting Words With a Given Prefix](./solutions/2185-counting-words-with-a-given-prefix.js)|Easy|
 2206|[Divide Array Into Equal Pairs](./solutions/2206-divide-array-into-equal-pairs.js)|Easy|

solutions/2176-count-equal-and-divisible-pairs-in-an-array.js

@@ -0,0 +1,34 @@
+/**
+ * 2176. Count Equal and Divisible Pairs in an Array
+ * https://leetcode.com/problems/count-equal-and-divisible-pairs-in-an-array/
+ * Difficulty: Easy
+ *
+ * Given a 0-indexed integer array nums of length n and an integer k, return the number of
+ * pairs (i, j) where 0 <= i < j < n, such that nums[i] == nums[j] and (i * j) is divisible by k.
+ */
+
+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @return {number}
+ */
+var countPairs = function(nums, k) {
+  const frequencyMap = new Map();
+  let result = 0;
+
+  nums.forEach((num, index) => {
+    if (frequencyMap.has(num)) {
+      const values = frequencyMap.get(num);
+      values.forEach(prevIndex => {
+        if ((prevIndex * index) % k === 0) {
+          result++;
+        }
+      });
+      values.push(index);
+    } else {
+      frequencyMap.set(num, [index]);
+    }
+  });
+
+  return result;
+};