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Question about the task

Under discussion

Can you optimize this code? I am trying to run it but it shows code took too long to run. Working fine in local machine.

1. Enter 20 numbers from the keyboard, save them in a list, and then sort them to three other lists:
Numbers divisible by 3 (x%3==0), numbers divisible by 2 (x%2==0), and all other numbers.
Numbers simultaneously divisible by 3 and 2 (for example 6) go into both lists.
The order in which the lists are declared is very important.
2. The printList method should display each list item on a new line.
3. Using the printList method, display these three lists. First, the list for x%3, then the list for x%2, and then the last list.

Requirements:

Declare and immediately initialize 4 ArrayList<Integer> variables. The first list will be the main one. The other lists will be supplementary.
Read 20 numbers from the keyboard and add them to the main list.
Add to the first supplementary list all numbers in the main list that are divisible by 3.
Add to the second supplementary list all numbers in the main list that are divisible by 2.
Add to the third supplementary list all the remaining numbers from the main list.
The printList method should display each element of the passed list on a new line.
The program should display the three supplementary lists using the printList method.

package com.codegym.task.task07.task0713; import java.io.BufferedReader; import java.io.InputStreamReader; import java.util.ArrayList; import java.util.List; import java.util.Scanner; /* Playing Javarella */ public class Solution { public static void main(String[] args) throws Exception { //write your code here Scanner k = new Scanner(System.in); ArrayList<Integer> mainList = new ArrayList<>( 20); for (int i = 0; i < 20 ; i++) { int n = k.nextInt(); mainList.add(n); } ArrayList<Integer> divBy3 = new ArrayList<>(); ArrayList<Integer> divBy2 = new ArrayList<>(); ArrayList<Integer> others = new ArrayList<>(); for (int i = 0; i < mainList.size() ; i++) { int n = mainList.get(i); if ((n % 3 ) == 0) { divBy3.add(n); if ((n % 2) == 0) divBy2.add(n); } else if ((n % 2) == 0) { divBy2.add(n); if ((n % 3 ) == 0) divBy3.add(n); } // if (((mainList.get(i) % 2) == 0) && ((mainList.get(i) % 3) == 0)) else others.add(n); } printList(divBy3); printList(divBy2); printList(others); } public static void printList(List<Integer> list) { //write your code here for (int i = 0; i < list.size(); i++) { System.out.println(list.get(i)); } } }

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Guadalupe Gagnon

Level 37 , Tampa, United States

4 June 2019, 15:37

They could have changed the validation since I have passed. The first requirement says to: "Declare and immediately initialize 4 ArrayList<Integer> variables. The first list will be the main one. The other lists will be supplementary." Try moving all four of you array lists to the top of the main method. Maybe that will pass?

Guadalupe Gagnon

Level 37 , Tampa, United States

29 May 2019, 15:54

There isn't anything wrong with that code to prevent verification. There must be something wrong with the verification system at this moment. You may need to wait a little bit and see if CodeGym resolves it on their end. You could also try this: at line 24 add k.nextLine(); Optimization: lines 40-41 will never be reached. If the number % 3 equals 0 then line 31 will be true and only that if block will be executed. It's not really optimization because it never gets executed, but you can clean your code up by removing it.

Anurag R Mishra

Level 16 , Rasipuram, India

4 June 2019, 13:19

Thanks for the help mate! But nothing much happened. Still the same issue. Too long to execute!