【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

 

 1 class Solution {

 2 public:

 3     bool isMatch(const char *s, const char *p) {

 4        

 5         if(*s=='\0'&&*p=='\0') return true;

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

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

 8        

 9         if(*p=='*')

10         {

11             while(*p=='*') p++;

12  

13            

14             while(*s!='\0')

15             {

16                 if(isMatch(s,p)) return true;

17                 s++;

18             }

19  

20    return isMatch(s,p);

21         }

22         else if(*p=='?')

23         {

24             return isMatch(s+1,p+1);

25         }

26         else

27         {

28             return (*s==*p&&isMatch(s+1,p+1));

29         }

30        

31        

32         return false;

33     }

34 };

 

 

 

 

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

……

 

 

 1 class Solution {

 2 public:

 3     bool isMatch(const char *s, const char *p) {

 4        

 5        

 6         const char* afterStarPositionP=NULL;

 7         const char* afterStarPositionS=NULL;

 8         while(*s!='\0')

 9         {

10             if(*s==*p||*p=='?')

11             {

12                 s++;p++;

13                 continue;

14             }

15             else if(*p=='*')

16             {

17                 p++;

18                 afterStarPositionP=p;

19                 afterStarPositionS=s;

20             }

21             else

22             {

23                 if(afterStarPositionP!=NULL)

24                 {

25                     afterStarPositionS++;

26                     s=afterStarPositionS;

27                     p=afterStarPositionP;

28                 }

29                 else

30                 {

31                     return false;

32                 }

33             }

34         }

35        

36         while(*p=='*')

37         {

38             p++;

39         }

40        

41         if(*p=='\0') return true;

42         else return false;

43     }

44 };