Added sieve

C++/sieve/yathansh.cpp

@@ -0,0 +1,29 @@
+// This functions finds all primes smaller than 'limit' 
+// using simple sieve of eratosthenes. 
+void simpleSieve(int limit) 
+{ 
+	// Create a boolean array "mark[0..limit-1]" and 
+	// initialize all entries of it as true. A value 
+	// in mark[p] will finally be false if 'p' is Not 
+	// a prime, else true. 
+	bool mark[limit]; 
+	memset(mark, true, sizeof(mark)); 
+
+	// One by one traverse all numbers so that their 
+	// multiples can be marked as composite. 
+	for (int p=2; p*p<limit; p++) 
+	{ 
+		// If p is not changed, then it is a prime 
+		if (mark[p] == true) 
+		{ 
+			// Update all multiples of p 
+			for (int i=p*2; i<limit; i+=p) 
+				mark[i] = false; 
+		} 
+	} 
+
+	// Print all prime numbers and store them in prime 
+	for (int p=2; p<limit; p++) 
+		if (mark[p] == true) 
+			cout << p << " "; 
+}