Leetcode 44: 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

 

 Solution 1: backtracking, works for regular cases but it times out for some long input.

public class Solution {
    public bool IsMatch(string s, string p) {
        return DFS(s, p, 0, 0);
    }
    
    private bool DFS(string s, string p, int sStart, int pStart)
    {
        if (sStart >= s.Length)
        {
            while (pStart < p.Length)
            {
                if (p[pStart] != '*') break;
                pStart++;
            }
            
            return pStart >= p.Length;
        }
        
        if (pStart >= p.Length) return false;
        
        if (p[pStart] == '?' || p[pStart] == s[sStart])
        {
            return DFS(s, p, sStart + 1, pStart + 1);
        }
        else if (p[pStart] == '*')
        {
            while (pStart < p. Length && p[pStart] == '*')
            {
                pStart++;
            }
            
            for (int i = sStart; i <= s.Length; i++)
            {
                if (DFS(s, p, i, pStart))
                {
                    return true;
                }
            }
        }
        
        return false;
    }
}

 

 There are both a linear sort of backtracking solution and a dp solution, please see leetcode.