Here is the optimized solution in Java. Copy or view it below.
Java
package Problems_On_Number;
import java.util.Scanner;
public class SumInRange {
public static void main(String args[]) {
Scanner sc = new Scanner(System.in);
System.out.println("enter the L value:");
int l = sc.nextInt();
System.out.println("enter the R value:");
int r = sc.nextInt();
// sum(1 to r) - sum(1 to l-1)
int ans = (r * (r + 1)) / 2 - ((l - 1) * (l)) / 2;
System.out.print("The sum of the numbers in the given range is " + ans);
sc.close();
}
}