added an algo which finds unique element in an array

Bit-Manipulation/UniqueElementInAnArray.js

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+/*
+ Problem Statement :
+
+ author : @dev-madhurendra
+
+ Question : https://leetcode.com/problems/unique-number-of-occurrences/
+
+ a) This algo works if all the element is repeating
+ twice except one element.
+
+ Explanation :
+ [1,2,1,2,3]
+ a) Basic thing is a^a (a xor a) = 0
+ b) So if we do like
+ 1^2^1^2^3 => (1^1)^(2^2)^3 => 0^0^3 => 3
+*/
+
+const UniqueElementInAnArray = (arr) => arr.reduce((acc, val) => acc ^ val, 0)
+
+export { UniqueElementInAnArray }

Bit-Manipulation/test/UniqueElementInAnArray.test.js

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+import { UniqueElementInAnArray } from '../UniqueElementInAnArray'
+
+describe('UniqueElementInAnArray', () => {
+ it.each([
+ [[1, 2, 1, 3, 3], 2],
+ [[1, 2, 3, 4, 5, 4, 3, 2, 1], 5]
+ ])('should return an unique element from an array', (arr, expected) => {
+ expect(UniqueElementInAnArray(arr)).toBe(expected)
+ })
+})