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Find the sum of non-prime elements in the given array

  • Difficulty Level : Hard
  • Last Updated : 13 Apr, 2021

Given an array arr[] and the task is to print the sum of the non-prime elements from the array.
Examples: 
 

Input: arr[] = {1, 3, 7, 4, 9, 8} 
Output: 22 
Non-prime elements are {1, 4, 9, 8} and 1 + 4 + 9 + 8 = 22
Input: arr[] = {11, 4, 10, 7} 
Output: 14 
 

 

Approach: Initialize sum = 0 and start traversing the array element by element, if current element is not a prime then update sum = sum + arr[i]. Print the sum in the end. Primality can be optimally tested using Sieve of Eratosthenes.
Below is the implementation of the above approach: 
 

C++




// CPP program to find sum of
// non-primes in given array
#include <bits/stdc++.h>
using namespace std;
 
// Function to return the sum of
// non-prime elements from the array
int nonPrimeSum(int arr[], int n)
{
    // Find maximum value in the array
    int max_val = *max_element(arr, arr + n);
 
    // USE SIEVE TO FIND ALL PRIME NUMBERS LESS
    // THAN OR EQUAL TO max_val
    // Create a boolean array "prime[0..n]". A
    // value in prime[i] will finally be false
    // if i is Not a prime, else true.
    vector<bool> prime(max_val + 1, true);
 
    // Remaining part of SIEVE
    prime[0] = false;
    prime[1] = false;
    for (int p = 2; p * p <= max_val; p++) {
 
        // If prime[p] is not changed, then
        // it is a prime
        if (prime[p] == true) {
 
            // Update all multiples of p
            for (int i = p * 2; i <= max_val; i += p)
                prime[i] = false;
        }
    }
 
    // Sum all non-prime elements in arr[]
    int sum = 0;
    for (int i = 0; i < n; i++)
        if (!prime[arr[i]])
            sum += arr[i];
 
    return sum;
}
 
// Driver code
int main()
{
 
    int arr[] = { 1, 3, 7, 4, 9, 8 };
    int n = sizeof(arr) / sizeof(arr[0]);
 
    cout << nonPrimeSum(arr, n);
 
    return 0;
}
Java



// Java program to find sum of
// non-primes in given array
import java.util.*;
 
class GFG
{
 
//returns the maximum element
static int max_element(int arr[])
{
    int max_e = Integer.MIN_VALUE;
    for(int i = 0; i < arr.length; i++)
    {
    max_e = Math.max(max_e, arr[i]);
    }
    return max_e;
}
 
// Function to return the sum of
// non-prime elements from the array
static int nonPrimeSum(int arr[], int n)
{
    // Find maximum value in the array
    int max_val = max_element(arr);
 
    // USE SIEVE TO FIND ALL PRIME NUMBERS LESS
    // THAN OR EQUAL TO max_val
    // Create a boolean array "prime[0..n]". A
    // value in prime[i] will finally be false
    // if i is Not a prime, else true.
    boolean prime[] = new boolean[max_val + 1];
     
    for(int i = 0; i < prime.length; i++)
    prime[i] = true;
 
    // Remaining part of SIEVE
    prime[0] = false;
    prime[1] = false;
    for (int p = 2; p * p <= max_val; p++)
    {
 
        // If prime[p] is not changed, then
        // it is a prime
        if (prime[p] == true)
        {
 
            // Update all multiples of p
            for (int i = p * 2; i <= max_val; i += p)
                prime[i] = false;
        }
    }
 
    // Sum all non-prime elements in arr[]
    int sum = 0;
    for (int i = 0; i < n; i++)
        if (!prime[arr[i]])
            sum += arr[i];
 
    return sum;
}
 
// Driver code
public static void main(String args[])
{
 
    int arr[] = { 1, 3, 7, 4, 9, 8 };
    int n = arr.length;
    System.out.println( nonPrimeSum(arr, n));
}
}
 
// This code is contributed by Arnab Kundu
Python3



# Python3 program to find sum of non-primes
# in given array
 
# from math lib. import sqrt
from math import sqrt
 
# Function to return the sum of
# non-prime elements from the array
def nonPrimeSum(arr, n) :
     
    # Find maximum value in the array
    max_val = max(arr)
 
    # USE SIEVE TO FIND ALL PRIME NUMBERS 
    # LESS THAN OR EQUAL TO max_val
    # Create a boolean array "prime[0..n]".
    # A value in prime[i] will finally be
    # false if i is Not a prime, else true.
    prime = [True] * (max_val + 1)
 
    # Remaining part of SIEVE
    prime[0] = False
    prime[1] = False
     
    for p in range(2, int(sqrt(max_val)) + 1) :
 
        # If prime[p] is not changed,
        # then it is a prime
        if (prime[p] == True) :
 
            # Update all multiples of p
            for i in range(p * 2, max_val + 1, p) :
                prime[i] = False
         
    # Sum all non-prime elements in arr[]
    sum = 0
    for i in range(0, n) :
        if (not prime[arr[i]]) :
            sum += arr[i]
 
    return sum
 
# Driver code
if __name__ == "__main__" :
 
    arr= [ 1, 3, 7, 4, 9, 8 ]
    n = len(arr)
 
    print(nonPrimeSum(arr, n))
 
# This code is contributed by Ryuga
C#



// C# program to find sum of non-primes
// in given array
using System;
 
class GFG
{
 
// returns the maximum element
static int max_element(int[] arr)
{
    int max_e = int.MinValue;
    for(int i = 0; i < arr.Length; i++)
    {
        max_e = Math.Max(max_e, arr[i]);
    }
    return max_e;
}
 
// Function to return the sum of
// non-prime elements from the array
static int nonPrimeSum(int[] arr, int n)
{
    // Find maximum value in the array
    int max_val = max_element(arr);
 
    // USE SIEVE TO FIND ALL PRIME NUMBERS
    // LESS THAN OR EQUAL TO max_val
    // Create a boolean array "prime[0..n]".
    // A value in prime[i] will finally be
    // false if i is Not a prime, else true.
    bool[] prime = new bool[max_val + 1];
     
    for(int i = 0; i < prime.Length; i++)
    prime[i] = true;
 
    // Remaining part of SIEVE
    prime[0] = false;
    prime[1] = false;
    for (int p = 2; p * p <= max_val; p++)
    {
 
        // If prime[p] is not changed,
        // then it is a prime
        if (prime[p] == true)
        {
 
            // Update all multiples of p
            for (int i = p * 2;
                     i <= max_val; i += p)
                prime[i] = false;
        }
    }
 
    // Sum all non-prime elements in arr[]
    int sum = 0;
    for (int i = 0; i < n; i++)
        if (!prime[arr[i]])
            sum += arr[i];
 
    return sum;
}
 
// Driver code
public static void Main()
{
    int[] arr = { 1, 3, 7, 4, 9, 8 };
    int n = arr.Length;
    Console.WriteLine(nonPrimeSum(arr, n));
}
}
 
// This code is contributed
// by Mukul Singh.
PHP



<?php
// PHP program to find sum of
// non-primes in given array
 
// Function to return the sum of
// non-prime elements from the array
function nonPrimeSum($arr, $n)
{
    // Find maximum value in the array
    $max_val = max($arr);
 
    // USE SIEVE TO FIND ALL PRIME NUMBERS LESS
    // THAN OR EQUAL TO max_val
    // Create a boolean array "prime[0..n]". A
    // value in prime[i] will finally be false
    // if i is Not a prime, else true.
    $prime = array_fill(0, $max_val + 1, true);
 
    // Remaining part of SIEVE
    $prime[0] = false;
    $prime[1] = false;
    for ($p = 2; $p * $p <= $max_val; $p++)
    {
 
        // If prime[p] is not changed, then
        // it is a prime
        if ($prime[$p] == true)
        {
 
            // Update all multiples of p
            for ($i = $p * 2;
                 $i <= $max_val; $i += $p)
                $prime[$i] = false;
        }
    }
 
    // Sum all non-prime elements in arr[]
    $sum = 0;
    for ($i = 0; $i < $n; $i++)
        if (!$prime[$arr[$i]])
             $sum += $arr[$i];
 
    return $sum;
}
 
// Driver code
$arr = array( 1, 3, 7, 4, 9, 8 );
$n = count($arr);
 
echo nonPrimeSum($arr, $n);
 
// this code is contributed by mits
?>
Javascript



<script>
 
// Javascript program to find sum of
// non-primes in given array
     
    //returns the maximum element
    function max_element(arr)
    {
        let max_e = Number.MIN_VALUE;
        for(let i = 0; i < arr.length; i++)
        {
            max_e = Math.max(max_e, arr[i]);
        }
        return max_e;
    }
     
    // Function to return the sum of
    // non-prime elements from the array
    function nonPrimeSum(arr,n)
    {
        // Find maximum value in the array
        let max_val = max_element(arr);
       
        // USE SIEVE TO FIND ALL PRIME NUMBERS LESS
        // THAN OR EQUAL TO max_val
        // Create a boolean array "prime[0..n]". A
        // value in prime[i] will finally be false
        // if i is Not a prime, else true.
        let prime = new Array(max_val + 1);
           
        for(let i = 0; i < prime.length; i++)
            prime[i] = true;
       
        // Remaining part of SIEVE
        prime[0] = false;
        prime[1] = false;
        for (let p = 2; p * p <= max_val; p++)
        {
       
            // If prime[p] is not changed, then
            // it is a prime
            if (prime[p] == true)
            {
       
                // Update all multiples of p
                for (let i = p * 2; i <= max_val; i += p)
                    prime[i] = false;
            }
        }
       
        // Sum all non-prime elements in arr[]
        let sum = 0;
        for (let i = 0; i < n; i++)
            if (!prime[arr[i]])
                sum += arr[i];
       
        return sum;
    }
     
    // Driver code
     
    let arr=[1, 3, 7, 4, 9, 8 ];
    let n = arr.length;
    document.write( nonPrimeSum(arr, n));
     
    // This code is contributed by unknown2108
     
</script>
Output: 
22
 

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mohit kumar 29
@mohit kumar 29
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