This is my first question on StackOverflow so please pardon any mistakes but let me know about them. I am trying to do problem 5 on Project Euler in Java. I feel like my code is correct but I can not get the answer.

What is the smallest positive number that is evenly divisible by all of the numbers from 1 to 20?

public class Main {
    public static void main(String[] args) {
        boolean a = true;
        int counter = 0;
        int b = 1;

        while (a) {
            for (int i = 1; i <= 20; i  ) { 
                if (b % i == 0) {
                    counter  ;
                }

                if (counter == 20) {
                    System.out.println(b);
                    a = false;
                }
                else {
                    b  ;
                }

                counter = 0;
            }
        }
    }
}

CodePudding user response：

The problem is that your nesting is wrong.

Within the for (int i = 1; i <= 20; i ) loop you increment counter if b is divisible by i.

The you do some checks and in the end set counter to zero again.

That means that your counter only ever reaches a maximum value of 1 (if b is divisible by a specific i).

You probably meant to write

        for (int i = 1; i <= 20; i  ) { 
            if (b % i == 0) {
                counter  ;
            }
        }

        if (counter == 20) {
            System.out.println(b);
            a = false;
        }
        else {
            b  ;
        }

        counter = 0;

which will give the correct result - although the algorithm is still terribly slow.