[LeetCode123]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

Analysis:
Greedy method

For each element in s

If *s==*p or *p == ? which means this is a match, then goes to next element s++ p++.

If p=='*', this is also a match, but one or many chars may be available, so let us save this *'s position and the matched s position.

If not match, then we check if there is a * previously showed up,

if there is no *, return false;

if there is an *, we set current p to the next element of *, and set current s to the next saved s position.

e.g.

abed

?b*d**

a=?, go on, b=b, go on,

e=*, save * position star=3, save s position ss = 3, p++

e!=d, check if there was a *, yes, ss++, s=ss; p=star+1

d=d, go on, meet the end.

check the rest element in p, if all are *, true, else false;

Note that in char array, the last is NOT NULL, to check the end, use "*p" or "*p=='\0'".

Java

public boolean isMatch(String s, String p) {
        int slen = s.length();
        int plen = p.length();
        int i = 0, j=0;
        int star = -1;
        int sp = 0;
        while(i<slen){
        	while(j<plen && p.charAt(j)=='*'){
        		star = j++;
        		sp = i;
        	}
        	if(j==plen || (s.charAt(i)!=p.charAt(j)&&p.charAt(j)!='?')){
        		if(star<0) return false;
        		else {
					j = star+1;
					i = sp++;
				}
        	}else {
				i++;
				j++;
			}
        }
        while(j<plen && p.charAt(j)=='*'){
        	j++;
        }
        return j == plen;
    }

c++

bool isMatch(const char *s, const char *p) {
        const char* star = NULL;
    const char* ss = s;
    while(*s){
        if((*p=='?') || *p==*s){
            s++;
            p++;
            continue;
        }
        if(*p=='*'){
            star = p++;
            ss = s;
            continue;
        }
        if(star){
            p = star+1;s=++ss;
            continue;
        }
        return false;
    }
    while(*p=='*'){p++;}
    return !*p;
    }