C++ Programming Code Examples
C++ > Data Structures Code Examples
C++ Program to Implement Hash Tables with Linear Probing
/* C++ Program to Implement Hash Tables with Linear Probing */
#include <iostream>
#include <cstdio>
#include <cstdlib>
using namespace std;
const int TABLE_SIZE = 5;
/* HashNode Class Declaration */
class HashNode
{
public:
int key;
int value;
HashNode(int key, int value)
{
this->key = key;
this->value = value;
}
};
/* DeletedNode Class Declaration */
class DeletedNode:public HashNode
{
private:
static DeletedNode *entry;
DeletedNode():HashNode(-1, -1)
{}
public:
static DeletedNode *getNode()
{
if (entry == NULL)
entry = new DeletedNode();
return entry;
}
};
DeletedNode *DeletedNode::entry = NULL;
/* HashMap Class Declaration */
class HashMap
{
private:
HashNode **htable;
public:
HashMap()
{
htable = new HashNode* [TABLE_SIZE];
for (int i = 0; i < TABLE_SIZE; i++)
{
htable[i] = NULL;
}
}
~HashMap()
{
for (int i = 0; i < TABLE_SIZE; i++)
{
if (htable[i] != NULL && htable[i] != DeletedNode::getNode())
delete htable[i];
}
delete[] htable;
}
/* Hash Function */
int HashFunc(int key)
{
return key % TABLE_SIZE;
}
/*Insert Element at a key */
void Insert(int key, int value)
{
int hash_val = HashFunc(key);
int init = -1;
int deletedindex = -1;
while (hash_val != init && (htable[hash_val]
== DeletedNode::getNode() || htable[hash_val]
!= NULL && htable[hash_val]->key != key))
{
if (init == -1)
init = hash_val;
if (htable[hash_val] == DeletedNode::getNode())
deletedindex = hash_val;
hash_val = HashFunc(hash_val + 1);
}
if (htable[hash_val] == NULL || hash_val == init)
{
if(deletedindex != -1)
htable[deletedindex] = new HashNode(key, value);
else
htable[hash_val] = new HashNode(key, value);
}
if(init != hash_val)
{
if (htable[hash_val] != DeletedNode::getNode())
{
if (htable[hash_val] != NULL)
{
if (htable[hash_val]->key == key)
htable[hash_val]->value = value;
}
}
else
htable[hash_val] = new HashNode(key, value);
}
}
/* Search Element at a key */
int Search(int key)
{
int hash_val = HashFunc(key);
int init = -1;
while (hash_val != init && (htable[hash_val]
== DeletedNode::getNode() || htable[hash_val]
!= NULL && htable[hash_val]->key != key))
{
if (init == -1)
init = hash_val;
hash_val = HashFunc(hash_val + 1);
}
if (htable[hash_val] == NULL || hash_val == init)
return -1;
else
return htable[hash_val]->value;
}
/*Remove Element at a key */
void Remove(int key)
{
int hash_val = HashFunc(key);
int init = -1;
while (hash_val != init && (htable[hash_val]
== DeletedNode::getNode() || htable[hash_val]
!= NULL && htable[hash_val]->key != key))
{
if (init == -1)
init = hash_val;
hash_val = HashFunc(hash_val + 1);
}
if (hash_val != init && htable[hash_val] != NULL)
{
delete htable[hash_val];
htable[hash_val] = DeletedNode::getNode();
}
}
};
/* Main Contains Menu */
int main()
{
HashMap hash;
int key, value;
int choice;
while(1)
{
cout<<"\n----------------------"<<endl;
cout<<"Operations on Hash Table"<<endl;
cout<<"\n----------------------"<<endl;
cout<<"1.Insert element into the table"<<endl;
cout<<"2.Search element from the key"<<endl;
cout<<"3.Delete element at a key"<<endl;
cout<<"4.Exit"<<endl;
cout<<"Enter your choice: ";
cin>>choice;
switch(choice)
{
case 1:
cout<<"Enter element to be inserted: ";
cin>>value;
cout<<"Enter key at which element to be inserted: ";
cin>>key;
hash.Insert(key, value);
break;
case 2:
cout<<"Enter key of the element to be searched: ";
cin>>key;
if(hash.Search(key) == -1)
{
cout<<"No element found at key "<<key<<endl;
continue;
}
else
{
cout<<"Element at key "<<key<<" : ";
cout<<hash.Search(key)<<endl;
}
break;
case 3:
cout<<"Enter key of the element to be deleted: ";
cin>>key;
hash.Remove(key);
break;
case 4:
exit(1);
default:
cout<<"\nEnter correct option\n";
}
}
return 0;
}
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