Add solution #1394

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,276 LeetCode solutions in JavaScript
+# 1,277 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -1063,6 +1063,7 @@
 1390|[Four Divisors](./solutions/1390-four-divisors.js)|Medium|
 1391|[Check if There is a Valid Path in a Grid](./solutions/1391-check-if-there-is-a-valid-path-in-a-grid.js)|Medium|
 1392|[Longest Happy Prefix](./solutions/1392-longest-happy-prefix.js)|Hard|
+1394|[Find Lucky Integer in an Array](./solutions/1394-find-lucky-integer-in-an-array.js)|Easy|
 1400|[Construct K Palindrome Strings](./solutions/1400-construct-k-palindrome-strings.js)|Medium|
 1402|[Reducing Dishes](./solutions/1402-reducing-dishes.js)|Hard|
 1408|[String Matching in an Array](./solutions/1408-string-matching-in-an-array.js)|Easy|

solutions/1394-find-lucky-integer-in-an-array.js

@@ -0,0 +1,30 @@
+/**
+ * 1394. Find Lucky Integer in an Array
+ * https://leetcode.com/problems/find-lucky-integer-in-an-array/
+ * Difficulty: Easy
+ *
+ * Given an array of integers arr, a lucky integer is an integer that has a frequency
+ * in the array equal to its value.
+ *
+ * Return the largest lucky integer in the array. If there is no lucky integer return -1.
+ */
+
+/**
+ * @param {number[]} arr
+ * @return {number}
+ */
+var findLucky = function(arr) {
+  const frequencyMap = new Map();
+  let result = -1;
+
+  for (const num of arr) {
+    frequencyMap.set(num, (frequencyMap.get(num) || 0) + 1);
+  }
+  for (const [num, count] of frequencyMap) {
+    if (num === count && num > result) {
+      result = num;
+    }
+  }
+
+  return result;
+};