数据结构--二路归并

package my;

public class MyMergeSort {

public static void mergeSort(int[] a, int left, int right, int[] b) {
   int mid = 0;

if (left < right) {
    mid = (left + right) / 2;
    mergeSort(a, left, mid, b);
    mergeSort(a, mid + 1, right, b);
    merge(a, left, mid, right, b);
    System.out.println("left mid right:"+left +" "+mid+" "+right);
   }
}// 归并排序

public static void merge(int[] a, int left, int mid, int right, int[] b) {

   int i = left;
   int j = mid + 1;
   int p = 0;

   while (i <= mid && j <= right) {
    b[p++] = (a[i] <= a[j]) ? a[i++] : a[j++];
   }//

   while (i <= mid)
    b[p++] = a[i++];
   while (j <= right)
    b[p++] = a[j++];

   for (p = 0, i = left; i <= right; i++, p++)
    a[i] = b[p];
}// 合并两个数组

public static void main(String[] args) {
   int[] a = { 21, 34, 56, 43, 99, 37 };
   int[] b = new int[a.length];// 辅助数组

   int left = 0;
   int right = a.length - 1;

   mergeSort(a, left, right, b);

   for (int i = 0; i <= right; i++)
    System.out.print(a[i] + " ");
}// main
}