实现一个简单的哈希表

#include <iostream>
#include <vector>
#include <list>
#include <random>
#include <ctime>
using namespace std;

const int hashsize = 12;

//定一个节点的结构体
template <typename T, typename U>
struct HashNode 
{
    T _key;
    U _value;
};

//使用拉链法实现哈希表类
template <typename T, typename U>
class HashTable
{
public:
    HashTable() : vec(hashsize) {}//类中的容器需要通过构造函数来指定大小
    ~HashTable() {}
    bool insert_data(const T &key, const U &value);
    int hash(const T &key);
    bool hash_find(const T &key);
private:
    vector<list<HashNode<T, U>>> vec;//将节点存储到容器中
};

//哈希函数（除留取余）
template <typename T, typename U>
int HashTable<T, U>::hash(const T &key)
{
    return key % 13;
}

//哈希查找
template <typename T, typename U>
bool HashTable<T, U>::hash_find(const T &key)
{
    int index = hash(key);//计算哈希值
    for (auto it = vec[index].begin(); it != vec[index].end(); ++it)
    {
        if (key == it -> _key)//如果找到则打印其关联值
        {
            cout << it->_value << endl;//输出数据前应该确认是否包含相应类型
            return true;
        }
    }
    return false;
}

//插入数据
template <typename T, typename U>
bool HashTable<T, U>::insert_data(const T &key, const U &value)
{
    //初始化数据
    HashNode<T, U> node;
    node._key = key;
    node._value = value;
    for (int i = 0; i < hashsize; ++i)
    {
        if (i == hash(key))//如果溢出则把相应的键值添加进链表
        {
            vec[i].push_back(node);
            return true;
        }
    }
}

int main(int argc, char const *argv[])
{
    HashTable<int, int> ht;
    static default_random_engine e;
    static uniform_int_distribution<unsigned> u(0, 100);
    long long int a = 10000000;
    for (long long int i = 0; i < a; ++i)
        ht.insert_data(i, u(e));
    clock_t start_time = clock();
    ht.hash_find(114);
    clock_t end_time = clock();
    cout << "Running time is: " << static_cast<double>(end_time - start_time) / CLOCKS_PER_SEC * 1000 <<
        "ms" << endl;//输出运行时间。
    system("pause");
    system("pause");
    return 0;
}