Added code of Sieve for finding prime numbers.

seiveofErssthones.cpp

@@ -0,0 +1,58 @@
+/*
+coded by - PATHAKCODES
+AIT PUNE , INDIA 
+
+"The Key is not will to win ......everybody has that "
+"It is will to prepare that is important"
+
+
+*/
+
+
+#include <bits/stdc++.h>
+
+using namespace std ;
+
+#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
+#define endl "\n"
+#define ll long long
+#define pb push_back
+const ll n  = 1000000 ;
+
+
+
+
+int main ()
+{
+	IOS
+	#ifndef ONLINE_JUDGE
+     freopen("input.txt", "r", stdin);
+     freopen("output.txt", "w", stdout);
+    #endif
+
+ll prime[n+1] ;
+ for(int i = 0 ; i <= n;i++)
+ {
+ 	prime[i] = 1 ;
+
+ }
+
+ prime[0] = 0 ;
+ prime[1] = 0 ;
+
+for(int j = 2 ; j<= sqrt(n) ; j++)
+{
+	if(prime[j] == 1)
+	{
+		for(int i = 2 ; i*j < n ; i++)
+			prime[i*j] = 0 ;
+	}
+}
+
+
+for (int i = 0; i < 22; ++i)
+{
+	cout << i << " " << prime[i] << endl ;
+}
+
+}