Question

我正在尝试使用堆来实现患者队列（root小于子）但是当我打印队列时，患者队列看起来没有优先级。

插入方法工作正常，但enqueue没有优先考虑项目？

// Heap class
.....some code

//insertion: inserts patients into minimum heap using an array.
//expand array as needed and reorder heap to maintain its properties

public void insert(ER_Patient patient) {
    if(heapArray.length==count)
        expand();
    heapArray[count] = patient;
    count++;
    if(count>1)
        reorder();
}

// Priority Queue class
.......some code

public void enqueue(ER_Patient patient) {
    try {
        heap.insert(patient);
    } catch (NoSuchCategoryException exception) {
        System.out.println("Can't enqueue");
    }

}

// copy content of original's array to a new larger array
private void expand(){
    ER_Patient[] tempArray = new ER_Patient[heapArray.length * 8];
    for(int i=0;i<=heapArray.length-1;i++)
        tempArray[i]=heapArray[i];
    heapArray = tempArray;
}

// maintain heap property by keeping roots smaller than children
private void reorder(){
    ER_Patient temp;
    int next = count -1;
    temp = heapArray[next];
    while((next!=0) && temp.compareTo(heapArray[(next-1)/2])<0){
        heapArray[next] = heapArray[(next-1)/2];
        next = (next-1)/2;
    }
    heapArray[next] = temp;
}

Answer 1

这就是我打印的方式：

public void display(Heap h)
{
    for(int i=0;i<h.count;i++)
        System.out.println(heapArray[i]);
}

错误。

除非您连续删除第一个项目并打印出来，否则您将无法获得有序列表。堆数组本身不是连续的。

Answer 2

重新排序方法的最后一行是否应该成为while循环的一部分？

heapArray[next] = temp;

此外，应该有适当的dequeue（）方法

堆优先级队列的实现？

2 个答案: