From 8dcb42c2bd74e8b368cb808eea36a0c404814114 Mon Sep 17 00:00:00 2001
From: Naveen Hegde <hegdenaveen1@gmail.com>
Date: Mon, 25 Dec 2017 14:39:09 +0530
Subject: [PATCH] Add Primality Test

removed bits/stdc++.h as suggested.
added brackets as suggested.
---
 Primality Test.cpp | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100644 Primality Test.cpp

diff --git a/Primality Test.cpp b/Primality Test.cpp
new file mode 100644
index 000000000..0b4bb67de
--- /dev/null
+++ b/Primality Test.cpp	
@@ -0,0 +1,33 @@
+#include <iostream>
+using namespace std;
+ 
+ 
+ //A simple and efficient implementation of a function to test if a number is prime, based on the fact that
+ //Every Prime number, except 2 and 3 are of the form 6*k+1 or 6*k-1 for integer values of k.
+ 
+ bool IsPrime( int number )
+ {
+  if ( ( (!(number & 1)) && number != 2 ) || (number < 2) || (number % 3 == 0 && number != 3) )
+    return false;
+
+    for( int k = 1; 36*k*k-12*k < number;++k)
+    {
+   	if ( (number % (6*k+1) == 0) || (number % (6*k-1) == 0) )
+        return false;		
+ 	}
+   return true;
+ }
+ 
+ int main()
+ {
+ 	//Main Function
+ 	cout <<"Enter the value of n to check if Prime\n";
+ 	int n;
+ 	cin >> n;
+ 	if(IsPrime(n))
+ 		cout << n << " is Prime" <<endl;
+ 	else	
+ 		cout << n << " is not Prime" <<endl;
+     
+ 	return 0;
+ }