merge method example

int[] temp = new int[last];
        int aMark = first, bMark = mid +1;
        for(int i = first; i<last; i++){
            if(aMark == mid && bMark < last) {
                temp[i] = a[bMark];
                bMark++;
            }
            else if(bMark == last && aMark < mid) {
                temp[i] = a[aMark];
                aMark++;
            }
            else if(aMark < mid && bMark<last) {
                if(a[aMark] < a[bMark]) {
                    temp[i] = a[aMark];
                    aMark++;
                }
                else {
                    temp[i] = a[bMark];
                    bMark++;
                }
            }

        }
        for(int j = first; j<last; j++)
            a[j] = temp[j];