maze quiz 5

private void merge(int[] a, int lo, int mid, int hi) {
    int[] aux = new int[a.length];
    for(int i = lo; i <= hi; i++) {
        aux[i] = a[i];
    }
    int i = lo;
    //what is missing here?
    for(int k = lo; k <= hi; k++) {
        if(i > mid) a[k] = aux[j++];
        else if(i > hi) a[k] = aux[i++];
        else if(aux[i] >= aux[j]) a[k] = aux[j++];
        else a[k] = aux[i++];
    }
}
private void sort(a[] a, int lo, int hi) {
    if(lo >= hi) return;
    int mid = lo + (hi - lo)/2;
    sort(a, lo, mid);
    sort(a, mid + 1, hi);
    merge(a, lo, mid, hi);
}
public void sort(a[] a) {
    sort(a, 0, a.length - 1);
}