void bubbleSort (void *seq[], int len, int (*cmp)(void *, void *)){
    void *t;
    for (; len--;){
        int flag = 0;
        for (int i = 0; i < len; i++){
            if (!(*cmp)(seq[i], seq[i+1])){
                t = seq[i];
                seq[i] = seq[i+1];
                seq[i+1] = t;
                flag = 1;
            }
        }
        if (!flag){
            break;
        }
    }
}