leetcode 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) {
        if (s.equals(p)) {
            return true;
        }
        
        int lenS=s.length();
        int lenP=p.length();
        if (lenP==0) {
            return lenS==0;
        }
        if (lenP==1) {
            if (p.equals(s)||(p.equals(".")&&lenS==1)) {
                return true;
            }else {
                return false;
            }
        }
        
        if (p.charAt(1)!='*') {
            if (lenS>0
                    &&(s.charAt(0)==p.charAt(0)||p.charAt(0)=='.')) {
                return isMatch(s.substring(1), p.substring(1));
            }
            return false;
        }else {
            while (s.length()>0&&
                    (s.charAt(0)==p.charAt(0)||p.charAt(0)=='.')) {
                if (isMatch(s, p.substring(2))) {
                    return true;
                }
                s=s.substring(1);
            }
            return isMatch(s, p.substring(2));
        }
    }
}