算法 3.9
void Merge (RcdType SR[], RcdType TR[], int i, int m, int n) {
      // 將有序的SR[i..m]和SR[m+1..n]歸并為有序的TR[i..n]
      for (j=m+1, k=i;  i<=m && j<=n;  ++k) {   // 將SR中記錄由小到大地并入TR
        if (SR[i].key<=SR[j].key)  TR[k] = SR[i++];
        else TR[k] = SR[j++];
      }
      while (i<=m) TR[k++] = SR[i++];          // 將剩余的SR[i..m]復(fù)制到TR
      while (j<=n) TR[k++] = SR[j++];          // 將剩余的SR[j..n]復(fù)制到TR
} // Merge