树形结构的数据结构（9）—— 大顶堆与小顶堆
最编程
2024-08-14 20:40:10
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package linearStructure.tree.heap;
import java.util.ArrayList;
import java.util.List;
public class MaxTopHeap {
//存储堆的数组
private int[] heap;
//堆的最大存储容量
private int maxSize;
//当前堆的存储数量
private int heapSize;
public MaxTopHeap(int maxSize) {
this.heap = new int[maxSize];
this.maxSize = maxSize;
this.heapSize = 0;
}
// 判断是否为空的方法
public boolean isEmpty() {
return heapSize == 0;
}
// 判断是否填满
public boolean isFull() {
return heapSize == maxSize;
}
// 获取堆顶的值
public int peek() throws Exception {
if (heapSize == 0) {
throw new Exception("heap is empty");
}
return heap[0];
}
// 往堆中添加值
public void insert (int value) throws Exception {
if (heapSize == maxSize) {
throw new Exception("head is full");
}
heap[heapSize] = value;
heapSize++;
buildMaxHeap(heap);
}
// 删除堆顶值
public int poll() throws Exception {
if (heapSize == 0) {
throw new Exception("heap is empty");
}
int ans = heap[0];
swap(heap,0,--heapSize);
buildMaxHeap(heap);
return ans;
}
// 建大顶堆
private int[] buildMaxHeap(int[] array) {
for (int i = (heapSize-2)/2; i >= 0; i--) {
adjustDownToUp(array,i,heapSize);
}
return array;
}
private void adjustDownToUp(int[] array, int index, int length) {
int temp = array[index];
for (int i = 2*index+1; i < length; i = 2*i+1) {
if (i < length-1 && array[i] < array[i+1]) {
i++;
}
if (temp >= array[i]) {
break;
} else {
array[index] = array[i];
index = i;
}
}
array[index] = temp;
}
// 交换元素值
private void swap(int[] arr, int i, int j) {
int temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
// 获取所有元素
public List<Integer> getAllElements() {
List<Integer> ans = new ArrayList<>();
for (int i = 0; i < heapSize; i++) {
ans.add(heap[i]);
}
return ans;
}
}