Bruteforce substring check

substring.md

isSubstring(String A, String B) {
    for i = 0 to len(A)-len(B) {
        j = 0;
        while j < len(B) and A[i+j] == B[j] {
            j = j + 1;
        }
        if j == len(B) {
            return True;
        }
    }
    return False;
}