Implement regular expression matching with support for '.' and '*'.
'.' Matches any single character.
'*' Matches zero or more of the preceding element.
The matching should cover the entire input string (not partial).
The function prototype should be:
bool isMatch(const char *s, const char *p)
Some examples:
isMatch("aa","a") → false
isMatch("aa","aa") → true
isMatch("aaa","aa") → false
isMatch("aa", "a") → true
isMatch("aa", ".") → true
isMatch("ab", ".") → true
isMatch("aab", "ca*b") → true
递归解法
#include <string>
using std::string;
class Solution {
public:
bool isMatch(string s, string p) {
if(p.empty()) return s.empty();
if(p.size()<2)
return !s.empty() && s.size() < 2 && (p[0] == s[0] || p[0] == '.');
if(p[1] == '*')
return isMatch(s, p.substr(2)) || !s.empty() && ((s[0] == p[0] || p[0] == '.') && isMatch(s.substr(1), p));
else
return !s.empty() && (s[0] == p[0] || p[0] == '.') && isMatch(s.substr(1), p.substr(1));
}
};
