HeapSort-堆排序-完全二叉树

import java.util.Arrays;

public class HeapSort {

	// 调用系统类库函数
	public static void comparator(int[] arr) {
		Arrays.sort(arr);

	}

	// 获取随机数组
	public static int[] getRandomArray(int maxSize, int maxValue) {
		int[] arr = new int[(int) ((maxSize + 1) * Math.random())];
		for (int i = 0; i < arr.length; i++) {
			// 获取 -maxVlaue + 1 ~ maxValue 的值
			arr[i] = (int) ((maxValue + 1) * Math.random()) - (int) (maxValue * Math.random());
		}

		return arr;

	}

	// 复制数组
	public static int[] copyArray(int[] arr) {
		if (arr == null) {
			return null;
		}
		int[] book = new int[arr.length];
		for (int i = 0; i < arr.length; i++) {
			book[i] = arr[i];
		}
		return book;
	}

	// 比较
	public static boolean isEqual(int[] arr1, int[] arr2) {
		if ((arr1 == null && arr2 != null) || (arr1 != null && arr2 == null)) {
			return false;
		}
		if (arr1 == null && arr2 == null) {
			return true;
		}
		if (arr1.length != arr2.length) {
			return false;
		}
		for (int i = 0; i < arr1.length; i++) {
			if (arr1[i] != arr2[i]) {
				return false;
			}
		}
		return true;

	}

	// 打印数组
	public static void printArray(int arr[]) {
		if (arr == null) {
			return;
		}
		for (int i = 0; i < arr.length; i++) {
			System.out.print(arr[i] + " ");
		}
		System.out.println();
	}

	public static void heapSort(int[] arr) {
		if (arr == null || arr.length < 2) {
			return;
		}
		for (int i = 0; i < arr.length; i++) {

			heapInsert(arr, i);

		}
		int heapsize = arr.length;
		// 第一个根节点位置确定
		swap(arr, 0, --heapsize);
		while (heapsize > 0) {
			heapIfy(arr, 0, heapsize);
			// 更新每一个堆的根节点
			swap(arr, 0, --heapsize);
		}

	}

	public static void swap(int[] arr, int i, int j) {
		int temp = arr[i];
		arr[i] = arr[j];
		arr[j] = temp;

	}

	public static void heapInsert(int[] arr, int index) {
		while (arr[index] > arr[(index - 1) / 2]) {
			swap(arr, index, (index - 1) / 2);
			index = (index - 1) / 2;
		}

	}

	public static void heapIfy(int[] arr, int index, int heapsize) {
		// 当前标记点的左节点
		int left = index * 2 + 1;
		while (left < heapsize) {
			// left+1为右节点,左右节点比较
			int largest = left + 1 < heapsize && arr[left + 1] > arr[left] ? left + 1 : left;
			// 比较之后的标记和原来标记自身比较
			largest = arr[largest] > arr[index] ? largest : index;
			if (index == largest) {
				return;
			}

			swap(arr, index, largest);
			// 更新标记点
			index = largest;
			left = largest * 2 + 1;

		}

	}

	public static void main(String[] args) {
		// 测试次数
		int test = 50000;

		// 数组长度
		int maxSize = 100;

		// 最大数值
		int maxValue = 100;
		boolean flag = true;
		for (int i = 0; i < test; i++) {
			int arr1[] = getRandomArray(maxSize, maxValue);
			// 拷贝比较
			int arr2[] = copyArray(arr1);
			heapSort(arr1);
			comparator(arr2);
			if (!isEqual(arr1, arr2)) {
				flag = true;
				break;
			}

		}
		System.out.println(flag ? "测试正常" : "发生错误");

		// 随机测试一组数据
		int arr[] = getRandomArray(maxSize, maxValue);
		printArray(arr);
		heapSort(arr);
		printArray(arr);

	}

}