725 分隔链表

    vector<ListNode *> splitListToParts(ListNode *root, int k) {
    vector<ListNode *> vec;
    if (root == nullptr) {
        for (; k > 0; --k)
            vec.push_back({});
        return vec;
    }
    int len = 0;
    ListNode *it = root;
    for (; it != nullptr; it = it->next, ++len);
    int nums = len / k;
    len -= (nums * k);
    if (nums == 0) {
        for (; k > 0; --k)
            if (root) {
                vec.push_back(root);
                ListNode *temp = root->next;
                root->next = nullptr;
                root = temp;
            } else
                vec.push_back({});
        return vec;
    }
    for (; k > 0; --k) {
        ListNode *temp_it = root;
        for (int temp = nums - 1; temp > 0; --temp)
            temp_it = temp_it->next;
        if (len > 0) {
            temp_it = temp_it->next;
            --len;
        }
        ListNode *temp_root = temp_it->next;
        temp_it->next = nullptr;
        vec.push_back(root);
        root = temp_root;
    }
    return vec;
}