# Leetcode Regular Expression Matching problem solution in Java

Feb 13, 2023

In the Leetcode Regular Expression Matching problem solution in Java programming Given an input string s and a pattern p, implement regular expression matching with support for ‘.’ and ‘*’ where:

‘.’ Matches any single character.
‘*’ Matches zero or more of the preceding element.
The matching should cover the entire input string (not partial).

## Leetcode Regular Expression Matching problem solution in Java programming

``````class Solution {
public boolean isMatch(String s, String p) {
return isMatch(s,p,'\0');
}

private boolean isMatch(String s,String p,char pred){

if(s.length()==0){
if(p.length()==0)
return true;
if(pred!='\0'){
return isMatch(s,p.substring(1),'\0');
}
else if(p.length()>1 && p.charAt(1)=='*'){
return isMatch(s,p.substring(2),'\0');
}
else
return false;
}

else if(p.length()==0)
return false;

else if(pred!='\0'){
if(s.charAt(0)==pred || pred=='.'){
return isMatch(s.substring(1),p,pred) || isMatch(s,p.substring(1),'\0');
}
else
return isMatch(s,p.substring(1),'\0');
}
else if(p.length()>1 && p.charAt(1)=='*'){
return isMatch(s,p.substring(1),p.charAt(0));
}
else if(s.charAt(0)==p.charAt(0) || p.charAt(0)=='.'){
return isMatch(s.substring(1),p.substring(1),'\0');
}
else
return false;

}

}``````

#### By Neha Singhal

Hi, my name is Neha singhal a software engineer and coder by profession. I like to solve coding problems that give me the power to write posts for this site.