I’m practicing algorithms and let’s say we have an array with elements 2, 3, 9, 12, 7, 18, then I want to print 18 only because it’s double of 9. When I print the result it always displays much more lines, however, the printed numbers (if there are any) are good. How can I manage displaying the result properly? (Using only arrays.) I know it’s a silly question but I tried so many ways and it was only worse.
Now, it shows me this for example (140 is correct, but the other line are not needed):
The following number is doubled of another number from the array: 0 The following number is doubled of another number from the array: 0 The following number is doubled of another number from the array: 140 The following number is doubled of another number from the array: 0 The following number is doubled of another number from the array: 0
My code:
public class DoubleNums {
public static void main(String[] args) {
Random random = new Random();
int[] array = new int[50];
int[] even;
int[] doubleNum;
int count = 0;
int doubles = 0;
for (int i = 0; i < array.length; i++) {
array[i] = random.nextInt(200);
System.out.println(array[i] + " ");
}
for (int j = 0; j < array.length; j++) {
even = new int[array.length];
if (array[j] % 2 == 0) {
even[count] = array[j];
count++;
}
for (int k = 0; k < array.length; k++) {
doubleNum = new int[array.length];
if (array[j] / 2 == array[k]) {
even[doubles] = k;
doubles++;
System.out.println("The following number is doubled of another number from the array: " + even[doubles]);
}
}
}
System.out.println("Number of even nums: " + count);
}
}
Answer
I saw that you asked for a solution that started with your own code…
I know it’s faster but I assumed that we can find a solution using my code with some minor changes.
So I tried to understand what you were trying to do and I have not been able to decipher your method so starting from your macro I created a clearer version.
Changes
- I used an ArrayList (
list) as support instead of your array (even). TheListis very convenient in your case because it has thecontains()function and also its size is variable. - I took an even number in the array and looked for if there was at least one “half” of it.
Code
public static void main(String[] args) {
Random random = new Random();
int[] array = new int[20];
ArrayList<Integer> list = new ArrayList<>();
int evenNumber = 0;
for (int i = 0; i < array.length; i++) {
array[i] = random.nextInt(100);
}
System.out.println(Arrays.toString(array));
for (int i = 0; i < array.length; i++) {
// If I found an even number and this is NOT already in the list then I'll study it
if (array[i] % 2 == 0 && !list.contains(array[i])) {
evenNumber = array[i];
for (int j = 0; j < array.length; j++) {
// I add "evenNumber" to the list only if at least one its "half" exist in the array
if (array[j] * 2 == evenNumber) {
list.add(evenNumber);
// I dont need to search more, I already found its "half"!
break;
}
}
}
}
System.out.println("Doubled nums: " + list);
}
Sample output
[71, 88, 45, 97, 64, 31, 54, 12, 14, 86, 22, 42, 35, 44, 70, 65, 93, 85, 99, 14] Doubled nums: [88, 44, 70]
