Find element in array that divides all array elements

• Difficulty Level : Easy
• Last Updated : 01 Apr, 2021

Given an array of n non-negative integers. Find such element in the array, that all array elements are divisible by it.
Examples :

```Input : arr[] = {2, 2, 4}
Output : 2

Input : arr[] = {2, 1, 3, 1, 6}
Output : 1

Input: arr[] = {2, 3, 5}
Output : -1```

The approach is to calculate GCD of the entire array and then check if there exist an element equal to the GCD of the array. For calculating the gcd of the entire array we will use Euclidean algorithm

C++

 `// CPP program to find such number in the array``// that all array elements are divisible by it``#include ``using` `namespace` `std;` `// Returns gcd of two numbers.``int` `gcd(``int` `a, ``int` `b)``{``    ``if` `(a == 0)``        ``return` `b;``    ``return` `gcd(b % a, a);``}` `// Function to return the``// desired number if exists``int` `findNumber(``int` `arr[], ``int` `n)``{``    ``// Find GCD of array``    ``int` `ans = arr[0];``    ``for` `(``int` `i = 0; i < n; i++)``        ``ans = gcd(ans, arr[i]);` `    ``// Check if GCD is present in array``    ``for` `(``int` `i = 0; i < n; i++)``        ``if` `(arr[i] == ans)``            ``return` `ans;` `    ``return` `-1;``}` `// Driver Function``int` `main()``{``    ``int` `arr[] = { 2, 2, 4 };``    ``int` `n = ``sizeof``(arr) / ``sizeof``(arr[0]);``    ``cout << findNumber(arr, n) << endl;``    ``return` `0;``}`

Java

 `// JAVA program to find such number in``// the array that all array elements``// are divisible by it``import` `java.io.*;` `class` `GFG {` `    ``// Returns GCD of two numbers``    ``static` `int` `gcd(``int` `a, ``int` `b)``    ``{``        ``if` `(a == ``0``)``            ``return` `b;``        ``return` `gcd(b % a, a);``    ``}` `    ``// Function to return the desired``    ``// number if exists``    ``static` `int` `findNumber(``int` `arr[], ``int` `n)``    ``{``        ``// Find GCD of array``        ``int` `ans = arr[``0``];``        ``for` `(``int` `i = ``0``; i < n; i++)``            ``ans = gcd(ans, arr[i]);` `        ``// Check if GCD is present in array``        ``for` `(``int` `i = ``0``; i < n; i++)``            ``if` `(arr[i] == ans)``                ``return` `ans;` `        ``return` `-``1``;``    ``}` `    ``// Driver Code``    ``public` `static` `void` `main(String args[])``    ``{``        ``int` `arr[] = { ``2``, ``2``, ``4` `};``        ``int` `n = arr.length;``        ``System.out.println(findNumber(arr, n));``    ``}``}` `// This code is contributed by Nikita Tiwari`

Python3

 `# Python3 program to find such number``# in the array that all array``# elements are divisible by it` `# Returns GCD of two numbers``def` `gcd (a, b) :``    ``if` `(a ``=``=` `0``) :``        ``return` `b``    ` `    ``return` `gcd (b ``%` `a, a)``    ` `# Function to return the desired``# number if exists``def` `findNumber (arr, n) :` `    ``# Find GCD of array``    ``ans ``=` `arr[``0``]``    ``for` `i ``in` `range``(``0``, n) :``        ``ans ``=` `gcd (ans, arr[i])``        ` `    ``# Check if GCD is present in array``    ``for` `i ``in` `range``(``0``, n) :``        ``if` `(arr[i] ``=``=` `ans) :``            ``return` `ans``    ` `    ``return` `-``1``    ` `# Driver Code``arr ``=` `[``2``, ``2``, ``4``];``n ``=` `len``(arr)``print``(findNumber(arr, n))` `# This code is contributed by Nikita Tiwari`

C#

 `// C# program to find such number in``// the array that all array elements``// are divisible by it``using` `System;` `class` `GFG {` `    ``// Returns GCD of two numbers``    ``static` `int` `gcd(``int` `a, ``int` `b)``    ``{``        ``if` `(a == 0)``            ``return` `b;``        ``return` `gcd(b % a, a);``    ``}` `    ``// Function to return the desired``    ``// number if exists``    ``static` `int` `findNumber(``int``[] arr, ``int` `n)``    ``{``        ``// Find GCD of array``        ``int` `ans = arr[0];``        ``for` `(``int` `i = 0; i < n; i++)``            ``ans = gcd(ans, arr[i]);` `        ``// Check if GCD is present in array``        ``for` `(``int` `i = 0; i < n; i++)``            ``if` `(arr[i] == ans)``                ``return` `ans;` `        ``return` `-1;``    ``}` `    ``// Driver Code``    ``public` `static` `void` `Main()``    ``{``        ``int``[] arr = { 2, 2, 4 };``        ``int` `n = arr.Length;``        ``Console.WriteLine(findNumber(arr, n));``    ``}``}` `// This code is contributed by vt_m`

PHP

 ``

Javascript

 ``

Output :

`2`

My Personal Notes arrow_drop_up