feat: Solving "Unique Number of Occurrences" (LeetCode | #1207 | Easy)

Author: brianr482

hash-maps/unique-number-occurrences.js

@@ -0,0 +1,35 @@
+/**
+ * LeetCode | #1207 | Easy
+ * 
+ * Given an array of integers arr, return true if the number of occurrences of each
+ * value in the array is unique or false otherwise.
+ * 
+ * Constraints:
+ * 1. 1 <= arr.length <= 1000
+ * 2. -1000 <= arr[i] <= 1000
+ * 
+ */
+
+/**
+ * Time complexity: O(n) - Space complexity: O(n)?
+ * 
+ * @param {number[]} arr
+ * @return {boolean}
+ */
+ function uniqueOccurrences(arr) {
+  if (arr.length === 1) {
+    return true;
+  }
+
+  const occurrencesMap = new Map();
+  for (const num of arr) {
+    const occurrences = occurrencesMap.has(num) 
+      ? occurrencesMap.get(num) + 1
+      : 1;
+
+    occurrencesMap.set(num, occurrences);
+  }
+  const occurrencesSet = new Set([...occurrencesMap.values()]);
+
+  return occurrencesSet.size === occurrencesMap.size;
+};