Create Sieve_of_Eratosthenes.cpp

Cpp/Sieve_of_Eratosthenes.cpp

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+#include <bits/stdc++.h>
+using namespace std;
+
+//
+
+vector<bool> Prime(3 * 1e6, true);
+
+void Sieve()
+{
+    Prime[1] = false;
+    for (long long i = 2; i * i <= Prime.size(); i++)
+    {
+        if (Prime[i] != true) // not prime
+            continue;
+        for (long long j = i * i; j < Prime.size(); j += i)
+        {
+            Prime[j] = false;
+        }
+    }
+}
+
+void solve()
+{
+    Sieve();
+    long long num;
+    cin >> num;
+    // 0 1 Format , 0 means not prime , 1 means prime
+    for (long long i = 2; i <= num; i++)
+    {
+        cout << i << " -> " << Prime[i] << "\n";
+    }
+    cout << "\n";
+
+    // word format
+    for (long long i = 2; i <= num; i++)
+    {
+        if (Prime[i])
+        {
+            cout << " " << i << " is a Prime number.\n";
+        }
+        else if (Prime[i] == 0)
+        {
+            cout << " " << i << " is not a Prime number.\n";
+        }
+    }
+}
+
+int main()
+{
+    ios_base::sync_with_stdio(0);
+    cin.tie(0);
+    long long int t;
+    t = 1;
+    while (t--)
+    {
+        solve();
+    }
+    return 0;
+}