Levenshtein 距离算法实现。Levenshtein 距离测量两个字符串的相近性-The "Levenshtein distance" is a measure of the similarity between two strings, this algorithm is also refered to as "edit distance".

又称Levenshtein距离（也叫做Edit Distance），是指两个字串之间，由一个转成另一个所需的最少编辑操作次数。许可的编辑操作包括将一个字符替换成另一个字符，插入一个字符，删除一个字符。 -Also known as Levenshtein distance (also known as Edit Distance), is between two strings, one by one turned into the minimum required number of edit