【leetcode】Wildcard Matching

Wildcard Matching

Implement wildcard pattern matching with support for '?' and '*'.

'?' Matches any single character.
'*' Matches any sequence of characters (including the empty sequence).

The matching should cover the entire input string (not partial).

The function prototype should be:
bool isMatch(const char *s, const char *p)

Some examples:
isMatch("aa","a") → false
isMatch("aa","aa") → true
isMatch("aaa","aa") → false
isMatch("aa", "*") → true
isMatch("aa", "a*") → true
isMatch("ab", "?*") → true
isMatch("aab", "c*a*b") → false

 

类似于Regular Expression Matching，会超时

 

class Solution {
public:
    bool isMatch(const char *s, const char *p) {
       
        if(*s==''&&*p=='') return true;
        if(*s!=''&&*p=='') return false;
        if(*s==''&&*p!='') return false;
       
        if(*p=='*')
        {
            while(*p=='*') p++;
 
           
            while(*s!='')
            {
                if(isMatch(s,p)) return true;
                s++;
            }
 
   return isMatch(s,p);
        }
        else if(*p=='?')
        {
            return isMatch(s+1,p+1);
        }
        else
        {
            return (*s==*p&&isMatch(s+1,p+1));
        }
       
       
        return false;
    }
};

 

 

 

采用类似回溯的思想

 

依次对字符进行比对，如果发现p=='*'

则从（p+1）开始和s开始依次比较，如果发现不对，

则回溯到（p+1）的位置，再从s+1开始依次比较

如果再不对，则再次回溯到(p+1)的位置，从s+2位置开始依次比较

……

 

 

class Solution {
public:
    bool isMatch(const char *s, const char *p) {
       
       
        const char* afterStarPositionP=NULL;
        const char* afterStarPositionS=NULL;
        while(*s!='')
        {
            if(*s==*p||*p=='?')
            {
                s++;p++;
                continue;
            }
            else if(*p=='*')
            {
                p++;
                afterStarPositionP=p;
                afterStarPositionS=s;
            }
            else
            {
                if(afterStarPositionP!=NULL)
                {
                    afterStarPositionS++;
                    s=afterStarPositionS;
                    p=afterStarPositionP;
                }
                else
                {
                    return false;
                }
            }
        }
       
        while(*p=='*')
        {
            p++;
        }
       
        if(*p=='') return true;
        else return false;
    }
};