CodingInterview/lc_44 at master · ssripadham/CodingInterview · GitHub

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/*
Given an input string (s) and a pattern (p), 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).

Note:

s could be empty and contains only lowercase letters a-z.
p could be empty and contains only lowercase letters a-z, and characters like ? or *.
Example 1:

Input:
s = "aa"
p = "a"
Output: false
Explanation: "a" does not match the entire string "aa".
Example 2:

Input:
s = "aa"
p = "*"
Output: true
Explanation: '*' matches any sequence.
Example 3:

Input:
s = "cb"
p = "?a"
Output: false
Explanation: '?' matches 'c', but the second letter is 'a', which does not match 'b'.
Example 4:

Input:
s = "adceb"
p = "*a*b"
Output: true
Explanation: The first '*' matches the empty sequence, while the second '*' matches the substring "dce".
Example 5:

Input:
s = "acdcb"
p = "a*c?b"
Output: false
*/

class Solution {

    bool isMatchUtil(string s, string p,int sIndex,int pIndex){

        if (p == "*") return true;
        if (pIndex == p.length()){
            return sIndex == s.length();
        }

        if (sIndex == s.length() && p[pIndex] != '*') {
            return pIndex == p.length();
        }

        if (s[sIndex] == p[pIndex] || p[pIndex] == '?'){
            //cout<<p[pIndex]<<" matches "<<s[sIndex]<<endl;
            return isMatchUtil(s,p,sIndex+1,pIndex+1);
        }

        if (p[pIndex] == '*'){
            //match 0,1...n upto sIndex.length()
            for (int i = sIndex; i <= s.length(); ++i) {
                cout<<i<<endl;
                if (isMatchUtil(s, p, i, pIndex+1)){
                    return true;
                }
            }
        }

        return false;

    }


public:
    bool isMatch(string s, string p) {

       return isMatchUtil(s, p, 0, 0);
    }
};