hgarbalere/hussaini-garba

Tasks 3

// CPP program to find count of // primes in given array. #include <bits/stdc++.h>

using namespace std;

// Function to find count of prime

int primeCount(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;

    }

}


// Find all primes in arr[]

int count = 0;

for (int i = 0; i < n; i++) 

    if (prime[arr[i]])

        count++;    


return count;

}

// Driver code

int main() {

int arr[] = { 1, 2, 3, 4, 5, 6, 7 };

int n = sizeof(arr) / sizeof(arr[0]);


cout << primeCount(arr, n);


return 0;

}