class Solution{
    public: 
        int strStr(string haystack, string needle){
            if(needle.length() > haystack.length()) return -1;
            for(int i =0;i <= haystack.length() - needle.length();i++){
                if(haystack.substr(i, needle.length()) == needle)
                    return i;
            }
            return -1;
        }
};

// TC : O(n*m)
// SC : O(m)
// m-> needle.length(), n-> haystack.length()