Added Prime Sieve

manav-06 · manav-06 · commit a675793acb6e · 2022-10-06T11:00:32.000+05:30
diff --git a/Miscellaneous/PrimeSieve.java b/Miscellaneous/PrimeSieve.java
@@ -0,0 +1,46 @@
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.ArrayList;
+import java.util.Arrays;
+
+public class PrimeSieve {
+
+    /*
+    For a given N, it will print all primes less than or equal to N
+     */
+    public static void main(String[] args) throws IOException {
+        System.out.println("Enter the N");
+
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+
+        int N = Integer.parseInt(br.readLine());
+
+        Boolean[] visited = new Boolean[N + 1];
+        Arrays.fill(visited, Boolean.FALSE);
+
+        ArrayList<Integer> primes = new ArrayList<>();
+
+        primes.add(2);
+
+        for (int i = 3; i * i <= N; i += 2) {
+            if (!visited[i]) {
+                for (int j = i * i; j <= N; j += 2 * i) {
+                    visited[j] = true;
+                }
+            }
+        }
+
+        for (int i = 3; i <= N; i += 2) {
+            if (!visited[i])
+                primes.add(i);
+        }
+
+        System.out.println("Primes <= N are:");
+
+        primes.forEach(System.out::println);
+
+        br.close();
+    }
+
+}
