#pragma once
#include<string>
using namespace std;
enum Status//表示当前位置的状态
{
EXITS,
DELETE,
EMPTY,
};
template<class K,class V>
struct KeyValueNode//KV键值对
{
K _key;
V _value;
KeyValueNode(const K& key=K(), const V& value=V())
:_key(key)
, _value(value)
{}
};
static size_t BKDRHash(const char * str)//哈希算法
{
unsigned int seed = 131; // 31 131 1313 13131 131313
unsigned int hash = 0;
while (*str )
{
hash = hash * seed + (* str++);
}
return (hash & 0x7FFFFFFF);
}
template<class K>//仿函数
struct HashFuner
{
size_t operator() (const K& key)
{
return key;
}
};
template<>//特化
struct HashFuner<string>
{
size_t operator() (const string& key)
{
return BKDRHash(key.c_str());
}
};
template<class K,class V,class HashFun = HashFuner<K> >
class HashTable
{
typedef KeyValueNode<K, V> KVNode;
public:
HashTable()
: _tables(NULL)
, _capacity(0)
, _size(0)
, _status(0)
{}
HashTable(int capacity)
:_tables(new KVNode[capacity])
, _capacity(capacity)
, _size(0)
, _status(new Status[capacity])
{
for (int i = 0; i < capacity; ++i)
{
_status[i] = EMPTY;
}
}
HashTable(const HashTable<K, V>& ht)
:_tables(NULL)
, _status(NULL)
{
HashTable<K, V> newtable(ht._capacity);
for (int i = 0; i < _capacity; ++i)
{
_tables[i]._key = ht._tables[i]._key;
_tables[i]._value = ht._tables[i]._value;
_size = ht._size;
_status[i] = ht._status[i];
}
this->Swap(newtable);
}
HashTable<K, V>& operator=(HashTable<K, V> ht)
{
this->Swap(ht);
return *this;
}
~HashTable()
{
if (_tables)
{
delete[] _tables;
delete[] _status;
}
}
public:
bool Insert(const K& key, const V& value)
{
if (_capacity == _size)
{
HashTable<K,V> newtables(_capacity * 2 + 1);
for (size_t i = 0; i < _capacity; ++i)
{
if (_status[i] == EXITS)
{
size_t index = HashFunc0(_tables[i]._key);
while (newtables._status[i] == EXITS)
{
index = HashFunc2(index, i++);
}
newtables._tables[index] = KVNode(_tables[i]._key,_tables[i]._value);
newtables._status[index] = EXITS;
++_size;
}
}
this->Swap(newtables);
}
size_t index = HashFunc0(key);
int i = 1;
while (_status[index] == EXITS)
{
index = HashFunc2(index, i++);
}
_tables[index] = KVNode(key, value);
_status[index] = EXITS;
_size++;
return true;
}
bool Remove(const K& key)
{
size_t index = HashFunc0(key);
int i = 1;
while (_tables[index] != EMPTY)
{
if (_tables[index]._key == key)
{
if (_status[index] == EXITS)
{
--_size;
_status[index] = DELETE;
return true;
}
else
{
return false;
}
}
index = HashFunc2(index, i++);
}
return false;
}
KVNode* Find(const K& key)
{
size_t index = HashFunc0(key);
int i = 0;
while (_status[index] != EMPTY)
{
if (key == _tables[index]._key)
{
if (_status[index] == EXITS)
return &_tables[index];
else
return NULL;
}
index = HashFunc2(index, i++);
}
return NULL;
}
size_t HashFunc0(const K& key)
{
return HashFun()(key) % _capacity;
}
size_t HashFunc2(size_t prevValue, int i)
{
return (prevValue + 2 * i - 1) % _capacity;
}
void Swap(HashTable<K, V, HashFun>& ht)
{
swap(_tables, ht._tables);
swap(_status, ht._status);
swap(_size, ht._size);
swap(_capacity, ht._capacity);
}
protected:
KVNode* _tables;
int _capacity;
int _size;
Status* _status;
};
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