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
}
}
}