408. Valid Word Abbreviation

Given a non-empty string s and an abbreviation abbr, return whether the string matches with the given abbreviation.

A string such as "word" contains only the following valid abbreviations:

["word", "1ord", "w1rd", "wo1d", "wor1", "2rd", "w2d", "wo2", "1o1d", "1or1", "w1r1", "1o2", "2r1", "3d", "w3", "4"]

Notice that only the above abbreviations are valid abbreviations of the string "word". Any other string is not a valid abbreviation of "word".

Note:
Assume s contains only lowercase letters and abbr contains only lowercase letters and digits.

Example 1:

Given s = "internationalization", abbr = "i12iz4n":

Return true.

Example 2:

Given s = "apple", abbr = "a2e":

Return false.

这里用正则表达式来进行匹配。"i12iz4n"如果换成正则式的形式，其实是"i.{12}iz.{4}n"，之后再调用string的matches函数，就能得到匹配结果。代码如下：

public class Solution {
    public boolean validWordAbbreviation(String word, String abbr) {
        return word.matches(abbr.replaceAll("[1-9]\\d*",".{$0}"));
    }
}