Sword finger offer regular expression matching

Regular Expression Matching

Subject requirements ：
Please implement a function to match including ’.‘ and ’‘ Regular expression of .
1. Characters in pattern ’.‘ Represents any character
2. Characters in pattern ’' Indicates that the character in front of it can appear any number of times （ contain 0 Time ）.
In the subject , Matching means that all characters of a string match the whole pattern . for example , character string "aaa" With the model "a.a" and "abaca" matching , But with the "aa.a" and "ab*a" No match

Solution code ：

class Solution {
public:
    /**
     *  The class name in the code 、 Method name 、 The parameter name has been specified , Do not modify , Return the value specified by the method directly 
     *
     * 
     * @param str string character string  
     * @param pattern string character string  
     * @return bool Boolean type 
     */
    bool match(string str, string pattern) {
        return MyMath(str, 0, pattern, 0);
    }
    
    // use i,j To indicate whether the subscript is better to judge whether it is out of bounds 
    bool MyMath(string str,int i,string patten,int j){
        // If str Traverse complete ,patten If the traversal is just completed , Indicates that the match is successful 
        if(i>=str.size() && j==patten.size()){
            return true;
        }
        // If str No traversal completed , however patten After traversal , Description matching failed 
        if(i<str.size() && j>=patten.size()){
            return false;
        }
        
        //patten The suffix is *
        if(patten[j+1]=='*' && (j+1)<patten.size()){
            //str and patten If the match is successful 
            if(i<str.size() && (str[i]==patten[j] || patten[j]=='.')){
                return (MyMath(str, i+1, patten, j) || MyMath(str, i, patten, j+2));
             }else{
                return MyMath(str, i, patten, j+2);
            }
        }
        
        if((str[i]==patten[j] || patten[j]=='.') && i<str.size()){
            return MyMath(str, i+1, patten, j+1);
        }
        return false;
        
    }
};