This is an improvement from a top

代码说明：

这是一个改进了自顶向下的归并排序，它改进的地方主要有：采用小子文件截止的机制，当序列长度小于32时，采用直接插入排序；对归并的内循环作了优化，判断的次数更少。-This is an improvement from a top-down sort of merger, it improved the main : the deadline for the paper boy mechanism, the length of the sequence is less than 32, the use of direct insertion sorting; Merging with the right circle made optimization, the number of less judgment.