算法导论11.2散列表Hash tables链式法解决碰撞11.3.1除法散列法
2015-02-12 12:53
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11.2是第11章的主要内容，11章叫散列表(HashTables)11.2也叫散列表(HashTables)
11.3节讲散列函数(比如除尘散列法)，11.4节讲处理碰撞的另外一种方法区别于链式法技术
散列技术，有两个事情要做，一是先哈希函数(11.3)，二是解决碰撞技术(11.2链式解决碰撞,11.4开放寻址解决碰撞）。
*IA_11.2ChainedHash.h
*
*Createdon:Feb13,2015
*Author:sunyj
*/
#ifndefIA_11_2CHAINEDHASH_H_
#defineIA_11_2CHAINEDHASH_H_
#include<iostream>
#include<string.h>
#include"IA_10.2LinkedLists.h"
//CHAINED-HASH-INSERT(T,x)
//insertxattheheadoflistT[h(x.key)]
//CHAINED-HASH-SEARCH(T,k)
//searchforanelementwithkeykinlistT[h(k)]
//CHAINED-HASH-DELETE(T,x)
//deletexfromthelistT[h(x.key)]
template<classT>classChainedHashTable{
public:
ChainedHashTable(int64_tconstn):size(n)
{
data=newLinkedList<int64_t,T>
();
}
~ChainedHashTable(){}
int64_tHashFunc(int64_tconstkey)
{
returnkey%size;
}
Node<int64_t,T>*search(int64_tconstkey)
{
returndata[HashFunc(key)].search(key);
}
//theuserofthisclass,hastoinvokesearchfirst
//thisinterfaceassumethatxwasnotinthehashtable
voidinsert(Node<int64_t,T>*x)
{
(data[HashFunc(x->key)]).insert(x);
}
voiddel(Node<int64_t,T>*x)
{
data[HashFunc(x->key)].del(x);
}
voidprint(int64_tkey)
{
data[HashFunc(key)].print();
}
private:
LinkedList<int64_t,T>*data;
int64_tconstsize;
};
#endif/*IA_11_2CHAINEDHASH_H_*/
*IA_11.2ChainedHash.cpp
*
*Createdon:Feb12,2015
*Author:sunyj
*/
#include"IA_11.2ChainedHash.h"
intmain()
{
/*
*Aprimenottooclosetoanexactpowerof2isoftenagoodchoiceform.For
example,supposewewishtoallocateahashtable,withcollisionsresolvedby
chaining,toholdroughlyn=2000characterstrings,whereacharacterhas8bits.
Wedon'tmindexamininganaverageof3elementsinanunsuccessfulsearch,and
soweallocateahashtableofsizem=701.Wecouldchoose701because
itisaprimenear2000=3butnotnearanypowerof2.
*/
ChainedHashTable<int64_t>table(701);//Thedivisionmethod,
Node<int64_t,int64_t>node1(1,100);
Node<int64_t,int64_t>node4(4,400);
Node<int64_t,int64_t>node16(16,1600);
Node<int64_t,int64_t>node9(9,900);
if(nullptr==table.search(node1.key))
{ //searchbeforeinsert
table.insert(&node1);
}
else
{
std::cout<<"node1alreadyexist"<<std::endl;
}
if(nullptr==table.search(node1.key))
{
table.insert(&node1);
}
else
{
std::cout<<"node1alreadyexist"<<std::endl;
}
table.insert(&node4);
table.insert(&node16);
table.insert(&node9);
table.print(4);
Node<int64_t,int64_t>node25(25,2500);
table.insert(&node25);
table.print(16);
//searchbeforedel,oryouareclearlysurethat,therearethisnodeexist.
//ifnode1isnotexist,andyouinvokedel,programwillcrush
table.del(&node1);
table.print(9);
Node<int64_t,int64_t>*tmp;
tmp=table.search(9);
table.del(tmp);
table.print(9);
return0;
}
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