Find integers that divides maximum number of elements of the array

Given an array arr[] of integers, the task is to find the element (other than 1) which is the factor of maximum number of elements from the array. If multiple such factors exist, print all the factors in ascending order.

Examples:

Input: arr[] = {10, 20}
Output: 2 5 10
The factors of 10 are 1, 2, 5, 10.
The factors of 20 are 1, 2, 4, 5, 10, 20.
The factors other than 1 which occur most number of times (twice) are 2, 5, 10.

Input: arr[] = {120, 15, 24, 63, 18}
Output: 3

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach:

Initialize two lists one to store the rank (the number of elements that the integer is a factor of) of the factor and another to store the factor.
Start from 2 till the maximum element of the array.
Count the number of elements from the array the current integer is a factor of.
Add the count to the rank list and the integer to factor list.
Find the integer with the maximum rank.
Print all the elements with the same rank.

Below is the implementation of the above approach:

C++

// CPP implementation of the approach 
#include<bits/stdc++.h> 
using namespace std; 
  
// Function to print the integers that divide  
// the maximum number of elements from the array 
void maximumFactor(vector<int>arr) 
{ 
    // Initialize two lists  
    // to store rank and factors 
    int n = arr.size(); 
    vector<int> rank; 
    vector<int> factors;  
    int max = *max_element(arr.begin(), arr.end());  
      
    // Start from 2 till the maximum element in arr 
    for (int i = 2; i <= max; i++) 
    { 
        // Initialize a variable 
        // to count the number of elements  
        // it is a factor of 
        int count = 0; 
        for (int j = 0; j < n; j++) 
        { 
            if (arr[j] % i == 0) 
                count+= 1; 
            rank.push_back(count); 
            factors.push_back(i); 
        }  
          
    } 
          
          
      
    // Maximum rank in the rank list 
    int m = *max_element(rank.begin(),rank.end()); 
    for (int i = 0; i < rank.size(); i++) 
    { 
        // Print all the elements with rank m 
        if (rank[i] == m) 
            cout << factors[i] <<" "; 
    } 
          
}  
  
// Driver code 
int main() 
{ 
    vector<int>arr = {120, 15, 24, 63, 18}; 
    maximumFactor(arr); 
} 
  
// This code is contributed by 
// Surendra_Gangwar 

Java

// Java implementation of the approach  
import java.util.*;  
class GFG 
{ 
      
// Function to print the integers that  
// divide the maximum number of  
// elements from the array 
static void maximumFactor(int []arr) 
{ 
      
    // Initialize two lists to store  
    // rank and factors  
    int[] rank = new int[Arrays.stream(arr).max().getAsInt() + 1]; 
    int[] factors = new int[Arrays.stream(arr).max().getAsInt() + 1]; 
    int g = 0; 
      
    // Start from 2 till the maximum 
    // element in arr  
    for (int i = 2;  
             i <= Arrays.stream(arr).max().getAsInt(); i++)  
    { 
        // Initialize a variable to count 
        // the number of elements it is a  
        // factor of  
        int count = 0; 
        for (int j = 0; j < arr.length; j++)  
            if (arr[j] % i == 0) 
                count += 1; 
                  
        rank[g] = count;  
        factors[g] = i; 
        g++; 
    } 
      
    // Maximum rank in the rank list  
    int m = Arrays.stream(rank).max().getAsInt(); 
    for (int i = 0; i < rank.length; i++)  
    { 
        // Print all the elements with rank m  
        if (rank[i] == m)  
            System.out.print(factors[i] + " ");  
    } 
}  
  
// Driver code 
public static void main (String[] args)  
{ 
    int []arr = {120, 15, 24, 63, 18}; 
    maximumFactor(arr);  
} 
} 
  
// This code is contributed by  
// chandan_jnu 

Python

# Python3 implementation of the approach 
  
# Function to print the integers that divide  
# the maximum number of elements from the array 
def maximumFactor(arr): 
      
    # Initialize two lists  
    # to store rank and factors 
    rank, factors = [], [] 
      
    # Start from 2 till the maximum element in arr 
    for i in range(2, max(arr)+1): 
          
        # Initialize a variable 
        # to count the number of elements  
        # it is a factor of 
        count = 0
        for j in arr: 
            if j % i == 0:count+= 1
        rank.append(count) 
        factors.append(i) 
      
    # Maximum rank in the rank list 
    m = max(rank) 
    for i in range(len(rank)): 
          
        # Print all the elements with rank m 
        if rank[i]== m: 
            print(factors[i], end =" ") 
  
# Driver code 
arr = [120, 15, 24, 63, 18] 
  
maximumFactor(arr) 

C#

// C# implementation of the approach  
using System; 
using System.Collections; 
using System.Linq; 
  
class GFG 
{ 
      
// Function to print the integers that  
// divide the maximum number of  
// elements from the array 
static void maximumFactor(int []arr) 
{ 
      
    // Initialize two lists to store  
    // rank and factors  
    int[] rank = new int[arr.Max() + 1]; 
    int[] factors = new int[arr.Max() + 1]; 
    int g = 0; 
      
    // Start from 2 till the maximum 
    // element in arr  
    for (int i = 2; i <= arr.Max(); i++)  
    { 
        // Initialize a variable to count 
        // the number of elements it is a  
        // factor of  
        int count = 0 ; 
        for (int j = 0; j < arr.Length; j++)  
            if (arr[j] % i == 0) 
                count += 1; 
                  
        rank[g]=count;  
        factors[g]=i; 
        g++; 
    } 
      
    // Maximum rank in the rank list  
    int m = rank.Max(); 
    for (int i = 0; i < rank.Length; i++)  
    { 
        // Print all the elements with rank m  
        if ((int)rank[i] == m)  
            Console.Write(factors[i]+" ");  
    } 
}  
  
// Driver code 
static void Main() 
{ 
  
int []arr = {120, 15, 24, 63, 18}; 
maximumFactor(arr);  
} 
} 
  
// This code is contributed by chandan_jnu 

PHP

<?php 
// PHP implementation of the approach  
  
// Function to print the integers that  
// divide the maximum number of  
// elements from the array 
function maximumFactor($arr) 
{ 
      
    // Initialize two lists to store  
    // rank and factors  
    $rank = array(); 
    $factors = array(); 
      
    // Start from 2 till the maximum 
    // element in arr  
    for ($i = 2; $i <= max($arr); $i++)  
    { 
        // Initialize a variable to count 
        // the number of elements it is a  
        // factor of  
        $count = 0 ; 
        for ($j = 0; $j < sizeof($arr); $j++)  
            if ($arr[$j] % $i == 0) 
                $count += 1; 
                  
        array_push($rank, $count);  
        array_push($factors, $i); 
    } 
      
    // Maximum rank in the rank list  
    $m = max($rank); 
    for ($i = 0; $i < sizeof($rank); $i++)  
    { 
        // Print all the elements with rank m  
        if ($rank[$i] == $m)  
            echo $factors[$i], " ";  
    } 
}  
  
// Driver code  
$arr = array(120, 15, 24, 63, 18); 
  
maximumFactor($arr)  
  
// This code is contributed by Ryuga 
?> 

Output:

GeeksforGeeks has prepared a complete interview preparation course with premium videos, theory, practice problems, TA support and many more features. Please refer Placement 100 for details

My Personal Notes

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

C++

Java

Python

C#

PHP

Recommended Posts: