28. Implement strStr()

class Solution {
    public int strStr(String haystack, String needle) {
        for(int i =0; ; i++){
            for(int j=0; ; j++){
                if (j == needle.length()) return i;
                if (i+j==haystack.length()) return -1;
                if (needle.charAt(j)!=haystack.charAt(i+j)) break;
            }
        }
    }
}