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).

RegExpMatch.java

public boolean isMatch(String str, String pat) {
    char[] s = str.toCharArray();
    char[] p = pat.toCharArray();
    boolean[][] dp = new boolean[s.length+1][p.length+1];

    dp[0][0] = true;

    for(int j = 1; j < dp[0].length; j++) { // For cases like (a, a*)
        if(p[j-1] == '*')
            dp[0][j] = dp[0][j-2];
    }

    for(int i = 1; i < dp.length; i++) {
        for(int j = 1; j < dp[0].length; j++) {
            if(p[j-1] == '.' || s[i-1] == p[j-1])
                dp[i][j] = dp[i-1][j-1];
            else if(p[j-1] == '*') {
                dp[i][j] = dp[i][j-2];
                if(s[i-1] == p[j-2] || p[j-2] == '.')
                    dp[i][j]  = dp[i][j] || dp[i-1][j];
            }
            else 
                dp[i][j] = false;
        }
    }

    return dp[s.length][p.length];
}