Added Sieve

SieveOfEratosthenes/SieveOfEratosthenes.cpp

@@ -0,0 +1,28 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+void SieveOfEratosthenes(int n)
+{
+    bool prime[n+1];
+    memset(prime, true, sizeof(prime));
+
+    for (int p=2; p*p<=n; p++)
+    {
+        if (prime[p] == true)
+        {
+            for (int i=p*p; i<=n; i += p)
+                prime[i] = false;
+        }
+    }
+    for (int p=2; p<=n; p++)
+       if (prime[p])
+          cout << p << " ";
+}
+
+int main()
+{
+    int n = 30;
+    cout << "Following are the prime numbers smaller than or equal to " << n << endl;
+    SieveOfEratosthenes(n);
+    return 0;
+}