【数据结构】排序--归并排序

public class SortUtil {

    /**
     * 归并排序采用递归
     * @param a
     * @param n
     */
    public static void Sort(int[] a, int n) {
        printData(a);
        mergeSort(a, 0, n - 1);
        printData(a);

    }

    public static int[] mergeSort(int a[], int low, int hight) {
        // 终止条件
        if (low < hight) {
            int mid = (hight + low) / 2;
            mergeSort(a, low, mid);
            mergeSort(a, mid + 1, hight);
            merge(a, low, hight);
        }


        return a;

    }

    public static void merge(int a[], int low, int hight) {
        int mid = (low + hight) / 2;
        int[] temp = new int[hight - low+1];
        int i = low;
        int j = mid + 1;
        int currentIndex = 0;
        while (i <= mid && j <= hight) {
            if (a[i] < a[j]) {
                temp[currentIndex++] = a[i];
                i++;
            } else {
                temp[currentIndex++] = a[j];
                j++;
            }

        }
        if (i <= mid) {
            for (; i <= mid; i++) {
                temp[currentIndex++] = a[i];
            }
        }

        if (j <= hight) {
            for (; j <= hight; j++) {
                temp[currentIndex++] = a[j];
            }
        }

        // 拷贝
        for (int m = 0; m < temp.length; m++) {
            a[low + m] = temp[m];
        }

    }

    private static void printData(int[] a) {
        StringBuffer stringBuffer = new StringBuffer();
        for (int i = 0; i < a.length; i++) {
            stringBuffer.append(a[i] + " ");
        }
        Log.d("zpb", "value:" + stringBuffer.toString());
    }
}