输入两个已经按从小到大顺序排列好的字符串，编写一个合并两个字符串的函数，使合并后的字符串，仍然是从小到 大排列。



输入：

两个已经排好顺序（升序）的两个字符串



输出：

一个合并在一起的有序（升序）的字符串



要求：

设计一个效率尽量高的算法，对每个字符串只扫描一遍就可以了。

如果采用先进行串连接，然后再进行排序的算法，则效率太低了。

-Enter both have small to large order, good strings to write a function merge two strings, so the string after the merger, is still ascending order. Input: two have been in good order (ascending) two string output: a combined ordered (ascending) string requirements: design an efficient algorithm is as high as possible, scan only once for each string on it. If you were using the first serial connection, and then sort of algorithm, the efficiency is too low.