28. Implement strStr()

class Solution {
    public int strStr(String haystack, String needle) {
        if(haystack.length() < needle.length()) {
            return -1;
        }
        if(haystack.length() == 0 || needle.length() == 0) return 0;
        System.out.println("test");
        boolean check = false;
        for(int i = 0;i < haystack.length();i++) {
            if(haystack.charAt(i) != needle.charAt(0) || i + needle.length() > haystack.length()) continue;
            check = true;
            for(int j = 1;j < needle.length();j++) {
                if(haystack.charAt(i+j) != needle.charAt(j)) {
                    check = false;
                    break;
                }
            }
            if(check) return i;
        }
        return -1;
    }
}