如何从堆的ArrayList实现中裁剪每个叶？

import java.util.ArrayList;

public class MinHeap {
    private ArrayList<Integer> heap;

    public MinHeap() {
        heap = new ArrayList<>();
    }

    public void insert(int value) {
        heap.add(value);
        heapifyUp(heap.size() - 1);
    }

    public int extractMin() {
        if (heap.isEmpty()) {
            throw new IllegalStateException("Heap is empty");
        }

        int minValue = heap.get(0);
        int lastIndex = heap.size() - 1;
        heap.set(0, heap.get(lastIndex));
        heap.remove(lastIndex);
        heapifyDown(0);

        return minValue;
    }

    private void heapifyUp(int index) {
        int parentIndex = (index - 1) / 2;

        while (index > 0 && heap.get(index) < heap.get(parentIndex)) {
            swap(index, parentIndex);
            index = parentIndex;
            parentIndex = (index - 1) / 2;
        }
    }

    private void heapifyDown(int index) {
        int leftChildIndex = 2 * index + 1;
        int rightChildIndex = 2 * index + 2;
        int smallestIndex = index;

        if (leftChildIndex < heap.size() && heap.get(leftChildIndex) < heap.get(smallestIndex)) {
            smallestIndex = leftChildIndex;
        }

        if (rightChildIndex < heap.size() && heap.get(rightChildIndex) < heap.get(smallestIndex)) {
            smallestIndex = rightChildIndex;
        }

        if (smallestIndex != index) {
            swap(index, smallestIndex);
            heapifyDown(smallestIndex);
        }
    }

    private void swap(int index1, int index2) {
        int temp = heap.get(index1);
        heap.set(index1, heap.get(index2));
        heap.set(index2, temp);
    }

    public static void main(String[] args) {
        MinHeap minHeap = new MinHeap();
        minHeap.insert(5);
        minHeap.insert(3);
        minHeap.insert(8);
        minHeap.insert(1);

        while (!minHeap.isEmpty()) {
            System.out.println(minHeap.extractMin());
        }
    }
}