// You can add your implementation here

private:

MemTable mMemTable{};

std::vector<Level> mLevel{};

std::string mDir{};

uint32_t mLevelNum = 0;

public:

explicit KVStore(const std::string &dir);

~KVStore();

void put(uint64_t key, const std::string &s) override;

std::string get(uint64_t key) override;

bool del(uint64_t key) override;

void reset() override;

void scan(uint64_t key1, uint64_t key2, std::list<std::pair<uint64_t, std::string> > &list) override;

void flush();