题目：
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.
链接：https://leetcode.com/problems/valid-word-abbreviation/#/description
3/22/2017
注意：
1. 第8行判断是否有leading的0，我认为这个属于invalid input。不过既然是google，需要仔细检查所有可能。
2. 遇到char时，index如何加，比较之后是否加。其实，在比较之后，之前inInteger的状态已经无所谓了，所以都需要+1
1 public class Solution { 2 public boolean validWordAbbreviation(String word, String abbr) { 3 boolean inInteger = false; 4 int number = 0; 5 int index = 0; 6 for (int i = 0; i < abbr.length(); i++) { 7 if (Character.isDigit(abbr.charAt(i))) { 8 if (!inInteger && abbr.charAt(i) - '0' == 0) return false; 9 number = number * 10 + abbr.charAt(i) - '0'; 10 inInteger = true; 11 } else { 12 if (inInteger) { 13 index += number; 14 inInteger = false; 15 number = 0; 16 } 17 if (index >= word.length()) return false; 18 if (word.charAt(index) != abbr.charAt(i)) return false; 19 index += 1; 20 } 21 } 22 if (inInteger) { 23 index += number; 24 } 25 if (index != word.length()) return false; 26 return true; 27 } 28 }
别人的思路：
1. 每次先比较2者是否相同，若不同查abbr是否是<=0或者>9（注意这里就排除了leading 0），再记录abbr index遍历abbr直到abbr的值不为数字，同时word加上中间的间隔。下次比较可以有结论。
2. 有个外国老哥，总是有很巧妙的方法：
1 public boolean validWordAbbreviation(String word, String abbr) { 2 return word.matches(abbr.replaceAll("[1-9]\d*", ".{$0}")); 3 }
其他讨论：https://discuss.leetcode.com/category/535/valid-word-abbreviation