Add: Exercise 1207. Unique Number of Occurrences

Author: BlackBeast593

1207-unique-numbers-of-occurrences/README.md

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+# 1207. Unique Number of Occurrences
+
+Given an array of integers `arr`, return `true` if the number of occurrences of each value in the
+array is unique or `false` otherwise.
+
+## Examples
+
+### Example 1:
+
+Input: `arr` = [1,2,2,1,1,3]  
+Output: `true`  
+Explanation: The value 1 has 3 occurrences, 2 has 2, and 3 has 1. No two values have the same number
+of occurrences.
+
+### Example 2:
+
+Input: `arr` = [1,2]  
+Output: `false`  
+
+### Example 3:
+
+Input: `arr` = [-3,0,1,-3,1,1,1,-3,10,0]  
+Output: `true`  
+
+## Constraints
+
+- 1 <= `arr.length` <= 1000
+- -1000 <= `arr[i]` <= 1000

1207-unique-numbers-of-occurrences/index.js

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+/**
+ * @param {number[]} arr
+ * @return {boolean}
+ */
+var uniqueOccurrences = function(arr) {
+    const numMap = {}
+    const freqMap = {}
+
+    for (let n of arr) {
+        numMap.hasOwnProperty(n) ? numMap[n]++ : numMap[n] = 1
+    }
+
+    for (let k in numMap) {
+        const freq = numMap[k]
+        freqMap.hasOwnProperty(freq) ? freqMap[freq]++ : freqMap[freq] = 1
+        if (freqMap[freq] > 1) {
+            return false
+        }
+    }
+
+    return true
+};
+
+var output = uniqueOccurrences([1,2])
+
+module.exports = uniqueOccurrences

1207-unique-numbers-of-occurrences/package.json

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+{
+  "name": "1207-unique-numbers-of-occurrences",
+  "version": "1.0.0",
+  "description": "Given an array of integers `arr`, return `true` if the number of occurrences of each value in the array is unique or `false` otherwise.",
+  "main": "index.js",
+  "scripts": {
+    "start": "node index.js",
+    "debug": "node --inspect-brk index.js",
+    "test": "node test.js"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC"
+}

1207-unique-numbers-of-occurrences/test.js

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+const assert = require('assert')
+const uniqueOccurrences = require('./index')
+
+const tests = [
+    {
+        arr: [1,2,2,1,1,3],
+        output: true,
+    },
+    {
+        arr: [1,2],
+        output: false,
+    },
+    {
+        arr: [-3,0,1,-3,1,1,1,-3,10,0],
+        output: true,
+    },
+]
+
+for (const t of tests) {
+    assert.strict.deepEqual(uniqueOccurrences(t.arr), t.output)
+}