java代码

class Solution {
    public boolean isMatch(String str, String pattern) {
        if (str == null || pattern == null) {
            return true;
        }
        int strIndex = 0;
        int patternIndex = 0;
        return matchCore(str.toCharArray(), strIndex, pattern.toCharArray(), patternIndex);
    }
    public boolean matchCore(char[] str, int strIndex, char[] pattern, int patternIndex) {
        //如果字符串与模式串同时访问完毕
        if(strIndex==str.length && patternIndex==pattern.length){
            return true;
        }
        //如果模式串访问完毕而字符串未访问完
        if(pattern.length==patternIndex && str.length!=strIndex){
            return false;
        }
        //如果模式串第二个字符是*那么
        if(patternIndex+1<pattern.length && pattern[patternIndex+1]=='*'){
            if(strIndex<str.length && matchChar(str[strIndex],pattern[patternIndex])){
//                System.out.println("1");
                return matchCore(str,strIndex+1,pattern,patternIndex) ||
                        matchCore(str,strIndex+1,pattern,patternIndex+2) ||
                        matchCore(str,strIndex,pattern,patternIndex+2);
            }else {
//                System.out.println("2");
                return matchCore(str,strIndex,pattern,patternIndex+2);
            }
        }
        if(strIndex<str.length && matchChar(str[strIndex],pattern[patternIndex])){
//            System.out.println("3");
            return matchCore(str,strIndex+1,pattern,patternIndex+1);
        }
        if(strIndex<str.length && !matchChar(str[strIndex],pattern[patternIndex])){
//            System.out.println("4");
            return false;
        }
//        System.out.println("5");
        return false;
    }
    public boolean matchChar(char ch1,char ch2){
        if(ch1==ch2||ch2=='.'){
            return true;
        }
        return false;
    }
}