class Solution { public boolean isMatch(String s, String p) { char[] str = s.toCharArray(), pat = p.toCharArray(); boolean[][] dp = new boolean[str.length + 1][pat.length + 1]; dp[0][0] = true; // dp[i][0] = false, 0 < i for (int i = 1; i <= pat.length; i++) dp[0][i] = 1 < i && pat[i - 1] == '*' && dp[0][i - 2]; for (int i = 1; i <= str.length; i++) { for (int j = 1; j <= pat.length; j++) { if (pat[j - 1] == '*') { dp[i][j] = dp[i][j - 2] || ((pat[j - 2] == '.' || str[i - 1] == pat[j - 2]) && dp[i - 1][j]); } else { dp[i][j] = (pat[j - 1] == '.' || str[i - 1] == pat[j - 1]) && dp[i - 1][j - 1]; } } } return dp[str.length][pat.length]; } }