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) {
        int mem[][] = new int [s.length()+1][p.length()+1];
        return match(s,0,p,0,mem);
    }
    public boolean match(String s,int is,String p,int ip,int[][]mem){
        if(ip>=p.length())return is==s.length();
        if(mem[is][ip]!=0) return mem[is][ip]==1;
        if(ip<p.length()-1 && p.charAt(ip+1)=='*'){
            while(ip<p.length() && is<s.length() && (s.charAt(is)==p.charAt(ip)||p.charAt(ip)=='.')){
                if(match(s,is,p,ip+2,mem)){
                    mem[is][ip] = 1;
                    return true;
                }
                is++;
            }
            return match(s,is,p,ip+2,mem);
        }
        else if(ip<p.length() && is<s.length() && (s.charAt(is)==p.charAt(ip)||p.charAt(ip)=='.')){
                return match(s,is+1,p,ip+1,mem);
            }
        else{
            mem[is][ip]=-1;
            return false;
        }
        
    }
}