leetcode

class Solution {
    public boolean isMatch(String s, String p) {
        if (s == null || p == null) {
            return false;
        }
        boolean[][] memo = new boolean[s.length()][p.length()];
        boolean[][] visited = new boolean[s.length()][p.length()];
        return helper(s, 0, p, 0, memo, visited);
    }
    private boolean helper(String s, int sIndex, String p, int pIndex, boolean[][] memo, boolean[][] visited) {
        if (pIndex == p.length()) {
            return s.length() == sIndex;
        }
        if (s.length() == sIndex) {
            return isAllStar(p, pIndex);
        }
        if (visited[sIndex][pIndex]) {
            return memo[sIndex][pIndex];
        }
        char pChar = p.charAt(pIndex);
        char sChar = s.charAt(sIndex);
        boolean match = false;
        if (pChar == '*') {
            if (p.charAt(pIndex - 1) == '.') {
                match = helper(s, sIndex + 1, p, pIndex, memo, visited) || helper(s, sIndex, p, pIndex + 1, memo, visited);
            } else {
                // if (sChar == p.charAt(pIndex - 1)) {
                //     match = helper(s, sIndex + 1, p, pIndex, memo, visited) || helper(s, sIndex, p, pIndex + 1, memo, visited);
                // } else {
                //     match = false;
                // }
                match = (sChar == p.charAt(pIndex - 1) && helper(s, sIndex + 1, p, pIndex, memo, visited)) || helper(s, sIndex, p, pIndex + 1, memo, visited);
            }
        } else {
//          "aab"
//          "c*a*b"
            if (pChar )
            match = (pChar == sChar || pChar == '.') && helper(s, sIndex + 1, p, pIndex + 1, memo, visited); 
        }
        visited[sIndex][pIndex] = true;
        memo[sIndex][pIndex] = match;
        return match;
    }
    private boolean isAllStar(String p, int pIndex) {
        for (int i = pIndex; i < p.length(); i++) {
            if (p.charAt(pIndex) != '*') {
                return false;
            }
        }
        return true;
    }
}

dp