归并排序

/**
 * 归并排序
 * <ul>
 * <li>平均情况：O(nlog(2)n)</li>
 * <li>最好情况：O(nlog(2)n)</li>
 * <li>最坏情况：O(nlog(2)n)</li>
 * <li>辅助存储：O(n)</li>
 * <li>稳定</li>
 * <ul>
 * 
 * @timestamp Mar 12, 2016 6:29:11 PM
 * @author smallbug
 */
public class MergeSort {

	public static void main(String[] args) {
		int[] data = DataUtil.getData(100000);
		// System.out.println(Arrays.toString(data));
		long time = System.currentTimeMillis();
		mergeSort(data);
		// System.out.println(Arrays.toString(data));
		System.out.println("speed " + (System.currentTimeMillis() - time) + " ms");
		System.out.println("排序是否成功：" + (DataUtil.verify(data, DataUtil.ASC) ? "是" : "否"));
	}

	private static void mergeSort(int[] data) {
		sort(data, 0, data.length - 1);
	}

	public static void sort(int[] data, int left, int right) {
		if (left >= right)
			return;
		// 找出中间索引
		int center = (left + right) >>> 1;
		// 对左边数组进行递归
		sort(data, left, center);
		// 对右边数组进行递归
		sort(data, center + 1, right);
		// 合并
		merge(data, left, right);
	}

	public static void merge(int[] data, int left, int right) {
		insertSort(data, left, right);
	}

	/**
	 * 局部插入排序
	 * 
	 * @timestamp Mar 12, 2016 6:28:30 PM
	 * @param data
	 * @param left
	 * @param right
	 */
	private static void insertSort(int[] data, int left, int right) {
		int temp;
		for (int i = left + 1; i <= right; i++) {
			temp = data[i];// 保存待插入的数值
			int j = i;
			for (; j > 0 && temp < data[j - 1]; j--) {
				data[j] = data[j - 1];// 如果待插入的数值前面的元素比该值大，就向后移动一位
			}
			data[j] = temp;// 插入
		}
	}
}