设有两个字符串s和t，首先将s1与t1进行比较，直到s的某一个字符si和ti相同，

再将它们之后的字符进行比较，若也相同，则如此继续往下比较，当s的某一个字符si与t的字符tj不同时，则s返回到本趟开始字符的下一个字符，即si-j+2，t返回到t1，继续开始下一趟的比较，重复上述过程。若t中的字符全部比较完，则说明本趟匹配成功，本趟的起始位置是i-j+1，否则，匹配失败。

-There are two strings s and t, first s1 and t1 compare s until one of the same characters si and ti, and then their characters after the comparison, if the same, then continue down such a comparison, when s a t a character si and tj characters not at the same time, it s back to the beginning of the trip the next character characters, that is si-j+ 2, t to return to the t1, continue to start the next trip comparison, repeat the process . If t compare all the characters in the End, then to match the success of this trip, this trip is the start position i-j+ 1, otherwise, the match failed.