Merge pull request #701 from IvanKuzaev/patch-1

Update PalindromicPrime.java

Misc/PalindromicPrime.java

@@ -1,15 +1,16 @@
 import java.util.Scanner;
+
 public class PalindromePrime {
 
     public static void main(String[] args) { // Main funtion
         Scanner in = new Scanner(System.in);
         System.out.println("Enter the quantity of First Palindromic Primes you want");
-        int n = in.nextInt(); // Input of how mant first pallindromic prime we want
-        funtioning(n); // calling funtion - functioning  
+        int n = in.nextInt(); // Input of how many first pallindromic prime we want
+        functioning(n); // calling function - functioning  
     }
 
     public static boolean prime(int num) { // checking if number is prime or not
-        for (int divisor = 2; divisor <= num / 2; divisor++) {
+        for (int divisor = 3; divisor <= Math.sqrt(num); divisor += 2) {
             if (num % divisor == 0) {
                 return false; //  false if not prime
             }
@@ -17,25 +18,27 @@ public class PalindromePrime {
         return true; // True if prime
     }
 
-    public static int reverse(int n){ //  Returns  the reverse of the number
+    public static int reverse(int n) { //  Returns  the reverse of the number
         int reverse = 0;
-        while(n!=0){
-            reverse = reverse * 10;
-            reverse = reverse + n%10;
-            n = n/10;
+        while(n != 0) {
+            reverse *= 10;
+            reverse += n%10;
+            n /= 10;
         }
         return reverse;
     }
 
-    public static void funtioning(int y){
-            int count =0;
-            int num = 2;
-            while(count < y){
-                if(prime(num) && num == reverse(num)){ // number is prime and it's reverse is same
-                    count++; // counts check when to terminate while loop
-                    System.out.print(num + "\n"); // Print the Palindromic Prime
-                }
-                num++; // inrease iterator value by one
+    public static void functioning(int y) {
+        if (y == 0) return;
+        System.out.print(2 + "\n"); // print the first Palindromic Prime
+        int count = 1;
+        int num = 3;
+        while(count < y) {
+            if(num == reverse(num) && prime(num)) { // number is prime and it's reverse is same
+                count++; // counts check when to terminate while loop
+                System.out.print(num + "\n"); // print the Palindromic Prime
             }
+            num += 2; // inrease iterator value by two
+        }
     }
-};
+}