Oct 22, 2025
diff --git a/Data-Structures/Array/SingleElement.js b/Data-Structures/Array/SingleElement.js
 /** https://leetcode.com/problems/single-number/description/
 * This function will accept an array and
 * Find an element which has only one frequency among other duplicate elements
 * The solution is based on using two loops, if the array is large, sorting or hashing is necessary, we can use XOR operator or sum method too
 * @param {Array} arr array with elements of integer type
 * @returns {Number} with single element
 */

 function SingleElement(arr) {
  let n = arr.length
  for (let i = 0; i < n; i++) {
    let count = 0
    // previous elements are already checked
    for (let j = 0; j < n; j++) {
      if (arr[j] === arr[i]) {
        count++
      }
    }
    if (count === 1) {
      return arr[i]
    }
  }
 }

 export { SingleElement }
diff --git a/Data-Structures/Array/test/SingleElement.test.js b/Data-Structures/Array/test/SingleElement.test.js
 import { SingleElement } from '../SingleElement'

 describe('single element in an array of duplicates', () => {
  test.each([
    [[1, 2, 2, 3, 3], 1],
    [[8, 9, 7, 2, 1, 5, 6, 4, 5, 9, 8, 7, 2, 6, 1], 4],
    [[10, 8, 5, 6, 8, 5, 6, 10, 11], 11]
  ])('returns %p when given %p', (array, expected) => {
    expect(SingleElement(array)).toBe(expected)
  })
 })
diff --git a/package-lock.json b/package-lock.json
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,25 @@
		/** https://leetcode.com/problems/single-number/description/
		* This function will accept an array and
		* Find an element which has only one frequency among other duplicate elements
		* The solution is based on using two loops, if the array is large, sorting or hashing is necessary, we can use XOR operator or sum method too
		* @param {Array} arr array with elements of integer type
		* @returns {Number} with single element
		*/

		function SingleElement(arr) {
		let n = arr.length
		for (let i = 0; i < n; i++) {
		let count = 0
		// previous elements are already checked
		for (let j = 0; j < n; j++) {
		if (arr[j] === arr[i]) {
		count++
		}
		}
		if (count === 1) {
		return arr[i]
		}
		}
		}

		export { SingleElement }
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,11 @@
		import { SingleElement } from '../SingleElement'

		describe('single element in an array of duplicates', () => {
		test.each([
		[[1, 2, 2, 3, 3], 1],
		[[8, 9, 7, 2, 1, 5, 6, 4, 5, 9, 8, 7, 2, 6, 1], 4],
		[[10, 8, 5, 6, 8, 5, 6, 10, 11], 11]
		])('returns %p when given %p', (array, expected) => {
		expect(SingleElement(array)).toBe(expected)
		})
		})