Prime Seive

/**
* @file
* @brief [Prime Seive](https://leetcode.com/problems/count-primes/)
* algorithm implementation.
* @author [Divyansh Kushwaha](https://github.com/webdesignbydivyansh)
*/
#include <assert.h>	/// for assert
#include <stdio.h>	/// for standard input output
#include <stdlib.h>	/// for general purpose standard library

const unsigned long long MAX_SIZE = 1000000;  /// variable upto which prime numbers are to be found out
/**
* @{
*/
/**
* @brief Prime Sieve works in O(nlogn) time
* @param p array to be updated
* @returns void
*/
void prime(int *p)
{
for(long long int i=3;i<=MAX_SIZE;i+=2) { p[i]=1; }
for(long long int i=3;i<=MAX_SIZE;i+=2)
{
if(p[i]==1) {
for(long long int j=i*i;j<=MAX_SIZE;j+=i) {
p[j]=0;
}
}
}
p[2]=1;
p[0]=p[1]=0;
}
/**
* @brief Count func counts the number of
* prime numbers.
* @param arr contains the prime numbers
* @param size denotes upto which prime numbers are to be found out
* @returns count of prime numbers
*/
int count(int *arr, const int size){
int k=0;
for(int i=0;i<=size;i++){
if(arr[i]==1){
k++;
}
}
return k;
}

/**
* @brief Test implementations
* @returns void
*/
static void test()
{
// Test Case 1
const int size = 10; /* array size */
printf("Test Case 1...");
int arr[1000005]={0};   /* array to store prime numbers */
prime(arr);
assert(count(arr,size)==4);
printf("Passed\n");
}

/**
* @brief Main function
* @param argc commandline argument count (ignored)
* @param argv commandline array of arguments (ignored)
* @returns 0 on exit
*/
int main(int argc, const char *argv[])
{
test();	// execute the tests
return 0;
}