问题是我正在尝试修复max heapify,但由于错误不断发生,它无法正常工作。我一直在阅读几本书中的伪代码,但仍然显示错误。我正在尝试使用A[i]
进行交换,将A[largest]
交换为=
,但是却给出了错误
class Heap {
// public for JUnit testing purposes
public ArrayList<Integer> array;
public int heap_size;
public Heap(int size) {
}
public Heap(List<Integer> source) {
this(source, false);
}
public Heap(List<Integer> source, boolean incremental) {
}
public static int parent(int index) {
return index/2;
}
public static int left(int index) {
return 2 * index;
}
public static int right(int index) {
return (2 * index) + 1;
}
public void maxHeapify(int i, int A)
{
int l = left(i);
int r = right(i);
if(l <= A.heap_size && A[l] > A[i])
largest = l;
else
largest = i;
if(r <= A.heap_size && A[r] > A[largest])
largest = r;
if(largest != i)
{
A[i] = A[largest];
maxHeapify(A,largest);
}
}
public void buildMaxHeap() {
}
public void insert(Integer k) {
}
public Integer maximum() {
return 0;
}
public Integer extractMax() {
return 0;
}
}
我希望它可以运行,但出现错误
Heap.java:31: error: int cannot be dereferenced
if(l <= A.heap_size && A[l] > A[i])
^
Heap.java:31: error: array required, but int found
if(l <= A.heap_size && A[l] > A[i])
^
Heap.java:31: error: array required, but int found
if(l <= A.heap_size && A[l] > A[i])
^
Heap.java:32: error: cannot find symbol
largest = l;
^
symbol: variable largest
location: class Heap
如果可以,请帮助。
答案 0 :(得分:0)
META.yml
是比较运算符。如果要分配值,则应使用==
运算符:
=
答案 1 :(得分:0)
根据错误消息,问题在于maxHeapify的参数A是一个整数值。您需要将参数A作为数组传递。
public void maxHeapify(int i, int[] A) {
int largest = i;
int l = left(i);
int r = right(i);
if(l < A.length && A[l] > A[largest])
largest = l;
if(r < A.length && A[r] > A[largest])
largest = r;
if(largest != i)
{
int tmp = A[i];
A[i] = A[largest];
A[largest] = tmp;
maxHeapify(largest, A);
}
}
我已经在以下代码中测试了上述maxHeapify。
public class HeapMain {
public static void main(String[] args) {
// Note: ignore the value at index 0
int[] A = new int[]{-1, 3, 9, 10, 4, 2, 33, 5};
Heap heap = new Heap(A.length);
for (int i = heap.parent(A.length - 1); i > 0; i--) {
heap.maxHeapify(i, A);
}
// You will get => 33 9 10 4 2 3 5
for (int i = 1; i < A.length; i++) {
System.out.print(A[i]);
System.out.print(" ");
}
System.out.println();
}
}
注意:parent,left和right方法假定数组中堆的节点是从索引1保存的。
以下网址可能会有所帮助。