I need assistance with this Java Array

Question

Return an array that contains the exact same numbers as the given array, but rearranged so that all the zeros are grouped at the start of the array. The order of the non-zero numbers does not matter. So {1, 0, 0, 1} becomes {0 ,0, 1, 1}. You may modify and return the given array or make a new array.

Answer 1

Keep 2 pointers, one at the start and the other which searches for 0s. If a zero is found, swap them, and move the pointers forward.

Answer 2

This probably isn't the fastest code, but for smaller arrays but I'd do something like this:

    for(int index = 0; index<array.length; index++ ){

        for(int search = index+1; search<array.length; search++){
            if(array[search]==0){
                int tempStorage = array[index];
                    array[index]= array[search];
                    array[search]= tempStorage;
            }
        }       
    }

Answer 3

Sort your array with a custom comparator (See https://docs.oracle.com/javase/7/docs/api/java/util/Arrays.html#sort(T[],%20java.util].Comparator).

In your comparator if it's not 0 then use the default int compare (See https://stackoverflow.com/a/9150459/241294).

Something like:

int compare(int a, int b)
{
  if (a == 0 && b == 0)
    return 0;
  if (a == 0)
    return -1;
  if (b == 0)
    return 1;
  else
    return Integer.compareTo(a, b);
}