the count of all numbers in range 1 to 106 inclusive which have minimum prime factor X

// C++ implementation of above approach 
#include <bits/stdc++.h> 
using namespace std; 
#define MAX 1000000 
  
// the sieve of prime number and 
// count of minimum prime factor 
int sieve_Prime[MAX + 4] = { 0 }, 
                      sieve_count[MAX + 4] = { 0 }; 
  
// form the prime sieve 
void form_sieve() 
{ 
    // 1 is not a prime number 
    sieve_Prime[1] = 1; 
  
    // form the sieve 
    for (int i = 2; i <= MAX; i++) { 
  
        // if i is prime 
        if (sieve_Prime[i] == 0) { 
            for (int j = i * 2; j <= MAX; j += i) { 
  
                // if i is the least prime factor 
                if (sieve_Prime[j] == 0) { 
  
                    // mark the number j as non prime 
                    sieve_Prime[j] = 1; 
  
                    // count the numbers whose least prime factor is i 
                    sieve_count[i]++; 
                } 
            } 
        } 
    } 
} 
  
// Driver code 
int main() 
{ 
    // form the sieve 
    form_sieve(); 
  
    int n = 2; 
  
    // display 
    cout << "Count = " << (sieve_count[n] + 1) << endl; 
  
    n = 3; 
  
    // display 
    cout << "Count = " << (sieve_count[n] + 1) << endl; 
  
    return 0; 
}