sieve.cpp

C++/sieve.cpp

@@ -0,0 +1,32 @@
+//Program to find the prime numbers in O(nloglogn)
+#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 << " "; 
+} 
+
+// Driver Program 
+int main() 
+{ 
+    int n = 1000; 
+    cout << "Here are the prime numbers smaller "
+         << " than or equal to " << n << endl; 
+    SieveOfEratosthenes(n); 
+    return 0; 
+}