From dfa3896c6296428b9f27891aac33da268b19b370 Mon Sep 17 00:00:00 2001
From: rnema19 <rnema19@Rishabh.localdomain>
Date: Wed, 22 Oct 2025 10:08:49 +0000
Subject: [PATCH] added new algorithm/problem in Array-DS

---
 Data-Structures/Array/SingleElement.js        | 25 +++++++++++++++++++
 .../Array/test/SingleElement.test.js          | 11 ++++++++
 package-lock.json                             | 13 +---------
 3 files changed, 37 insertions(+), 12 deletions(-)
 create mode 100644 Data-Structures/Array/SingleElement.js
 create mode 100644 Data-Structures/Array/test/SingleElement.test.js

diff --git a/Data-Structures/Array/SingleElement.js b/Data-Structures/Array/SingleElement.js
new file mode 100644
index 0000000000..5281c90617
--- /dev/null
+++ b/Data-Structures/Array/SingleElement.js
@@ -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 }
diff --git a/Data-Structures/Array/test/SingleElement.test.js b/Data-Structures/Array/test/SingleElement.test.js
new file mode 100644
index 0000000000..81fdcf1ade
--- /dev/null
+++ b/Data-Structures/Array/test/SingleElement.test.js
@@ -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)
+  })
+})
diff --git a/package-lock.json b/package-lock.json
index 5c38ba06a8..6b61c5260c 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -745,16 +745,6 @@
       "dev": true,
       "license": "MIT"
     },
-    "node_modules/@types/node": {
-      "version": "20.11.6",
-      "dev": true,
-      "license": "MIT",
-      "optional": true,
-      "peer": true,
-      "dependencies": {
-        "undici-types": "~5.26.4"
-      }
-    },
     "node_modules/@vitest/coverage-v8": {
       "version": "1.2.1",
       "dev": true,
@@ -1909,8 +1899,7 @@
       "version": "5.26.5",
       "dev": true,
       "license": "MIT",
-      "optional": true,
-      "peer": true
+      "optional": true
     },
     "node_modules/v8-to-istanbul": {
       "version": "9.2.0",