Method downheap

lectures/27-huffman-coding/code/Heap.java:48–68

(int index)

    }

    private void downheap(int index) {

        int min = index;
        int left = left(index);
        int right = right(index);

        // check is left < min
        if(left < list.size() && list.get(min).compareTo(list.get(left)) > 0){
            min = left;
        }
        // check if right < min
        if(right < list.size() && list.get(min).compareTo(list.get(right)) > 0){
            min = right;
        }

        if(min != index){
            swap(min, index);

            downheap(min);
        }
    }

    private void swap(int first, int second) {
        T temp = list.get(first);