hashtable实现（未编译）

最新推荐文章于 2024-08-02 16:32:59 发布

wlhwaii

最新推荐文章于 2024-08-02 16:32:59 发布

阅读量211

点赞数

CC 4.0 BY-SA版权

分类专栏： c++ 文章标签： c++ hashtable

本文链接：https://blog.youkuaiyun.com/wlhwaii/article/details/78300314

c++ 专栏收录该内容

6 篇文章

订阅专栏

本文介绍了一个使用C++实现的通用哈希表模板类。该类支持字符串键和任意类型值的存储，并提供了插入和查找操作。文章展示了如何定义哈希函数及处理冲突的方法。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

#include <iostream>
using namespace std;

template<typename Value_type>
    struct tagEntry{
    string _key;
    Value_type _value;
    struct tagEntry<Value_type>* _pNext;
    tagEntry(string k, Value_type v):_key(k), _value(v), _pNext(NULL){}

};

template<typename Value_type>
    class Hashtable {
    typedef struct tagEntry<Value_type> Entry;
    public:
    Hashtable(){
        _capacity = 31;
        _size = 0;
        _ptable = new *Entry[_capacity];    
    }
    ~Hashtable(){
        _size = 0;
        for (int i = 0; i < _capacity; i++) {
            Entry* cur = _ptable[i];
            while(cur) {
                Entry* tmp = cur;
                cur = cur->_pNext;
                delete cur;
            }
        }
        _capacity = 0;
        delete[] _ptable;
    }
    size_t size() {return _size;}
    void insert(string& key, Value_type& value) {
        _Expand();
        size_t index = hasher(key) % _capacity;
        Entry* pEntry = _ptable[index];
        if (!pEntry)
            pEntry = new Entry(key, value);
        else {
            while (pEntry->_pNext) 
                pEntry = pEntry->_pNext;
            pEntry->_pNext = new Entry(key, value);
        }
        _size++;
        return;
    }
    Value_Type& find(const string& key) {
        size_t = index hasher(key) & _capacity;
        Entry* pEntry = _ptable[index];
        while (pEntry) {
            if (pEntry->_key != key)
                pEntry = pEntry->_pNext;
            else
                return pEntry->_value;
        }
        return;
    }
    private:
    Entry** _ptable;
    size_t _capacity;
    size_t _size;
    void insert(Entry* node) {
        size_t index = haser(cur->key) & _capacity;
        Entry* pEntry = _ptable[index];
        if (!pEntry)
            pEntry = node;
        else {
            while (pEntry->_pNext)
                pEntry = pEntry->_pNext;
            pEntry->_pNext = node;
        }
    }
    void _Expand() {
        if (_size < _capacity)
            return;
        size_t new_capacity = _capacity * 2;
        Entry* pold_table = _ptable;
        _ptable = new *Entry[_capacity];
        for (int i = 0; i < _capacity; i++) {
            Entry *cur = pold_table[i];
            while(cur) {
                insert(cur);
                cur = cur->_pNext;
            }
            return;

        }
        size_t hasher(string& s) {
            register size_t h = 0;
            for(string::iterator iter = s.begin(); iter != s.end(); iter++)
                h = h*31 + *iter;
            return h;
        }    
    };

int main() {
    // your code goes here
    Hashtable<int> table;

    table.insert("abc",1);
    table.insert("bcd",2);

    cout<<table.find("abc")<<" "<<table.find("bcd")<<endl;
}