【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=='\0'&&*p=='\0') return true;
         if(*s!='\0'&&*p=='\0') return false;
         if(*s=='\0'&&*p!='\0') return false;

         if(*p=='*')
         {
             while(*p=='*') p++;

             while(*s!='\0')
             {
                 if(isMatch(s,p)) return true;
                 s++;
             }

    return isMatch(s,p);
         }
         else if(*p=='?')
         {
             return isMatch(s+,p+);
         }
         else
         {
             return (*s==*p&&isMatch(s+,p+));
         }

         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!='\0')
         {
             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=='\0') return true;
         else return false;
     }
 };