Regular Expression Matching
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", "c*a*b") → true
public class Solution { public boolean isMatch(String s, String p) { // Start typing your Java solution below // DO NOT write main() function if(s.equals(p)) return true; else if(s.length()==0&&p.length()==0) return true; else if(p.length()==0) return false; else if(s.length()==0){ if((p.length()>1&&p.charAt(1)!='*')||(p.length()<2)) return false; else return isMatch(s,p.substring(2));} else if(p.length()>1&&p.charAt(1)=='*'){ if(isMatch(s,p.substring(2))) return true; char a=(p.charAt(0)=='.')?s.charAt(0):p.charAt(0); int i=0; while(i<s.length()&&s.charAt(i)==a){ if(isMatch(s.substring(i+1),p.substring(2))) return true; i++;} } else if(s.charAt(0)!=p.charAt(0)&&p.charAt(0)!='.') return false; else return isMatch(s.substring(1),p.substring(1)); return false; } }