编译原理-词法分析，有三类子串：a，每个1右边都有一个0直接跟着；b:至少包含两个1，任意2个1之间包含偶数个0；c:不包含连续的子串100！输入一串字符，判断该串是哪一类别-Compiler theory- lexical analysis, there are three sub-string: a, each one on the right has a 0 followed immediately　b: at least two one, between any two 1 contains an even number of 0　c: does not contain the successive sub-string 100! Enter a string of characters, to determine which of the categories of the string is