Method swap

lectures/27-huffman-coding/code/Heap.java:70–74

(int first, int second)

    }

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

    private int parent(int index){
        return (index - 1) / 2;