合并排序是建立在归并操作上的一种有效的排序算法。该算法是采用分治法（Divide and Conquer）的一个非常典型的应用。合并排序法是将两个（或两个以上）有序表合并成一个新的有序表，即把待排序序列分为若干个子序列，每个子序列是有序的。然后再把有序子序列合并为整体有序序列。将已有序的子序列合并，得到完全有序的序列；即先使每个子序列有序，再使子序列段间有序。若将两个有序表合并成一个有序表，称为2-路归并。合并排序也叫归并排序。(Merge sort is an efficient sorting algorithm based on merging operations. This algorithm is a very typical application of Divide and Conquer. The merge sort method is to merge two or more ordered tables into a new ordered table, that is to say, the sorted sequence is divided into several sub sequences, each of which is ordered. (two). Then the ordered subsequence is merged into the whole ordered sequence. The sequence of ordered subsequences is combined to obtain the sequence of complete order, that is, each subsequence is ordered, and then the subsequence is ordered. If two ordered tables are merged into an ordered table, called 2- path merging. Merge sort is also called merge sort.)