10. Regular Expression Matching

yPhantom 2019年10月30日 47次浏览
class Solution {
    public boolean isMatch(String s, String p) {
        int m = s.length();
        int n = p.length();
        boolean[][] dp = new boolean[m + 1][n + 1];
        dp[0][0] = true;
        for (int j = 1; j <= n; j++) {
            if(p.charAt(j - 1) == '*' && dp[0][j - 2]){
                dp[0][j] = true;
            }
        }
        for (int i = 1; i <= m; i++) {
            for (int j = 1; j <= n; j++) {
                if (s.charAt(i - 1) == p.charAt(j - 1) || p.charAt(j - 1) == '.') {
                    dp[i][j] = dp[i - 1][j - 1];
                } else if (p.charAt(j - 1) == '*') {
                    if (s.charAt(i - 1) != p.charAt(j - 2) && p.charAt(j - 2) != '.') {
                        dp[i][j] = dp[i][j - 2];
                    } else {
                        dp[i][j] = dp[i - 1][j] || dp[i][j - 1] || dp[i][j - 2];
                    }
                }
            }
        }
        return dp[m][n];
    }
}