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C++ Program to Implement Hash Tables chaining with Singly Linked Lists
A hash table is a data structure which is used to store key-value pairs. Hash function is used by hash table to compute an index into an array in which an element will be inserted or searched.
This is a C++ program to Implement Hash Tables chaining with singly linked lists.
Algorithm
For insert:
Begin Declare Function Insert(int k, int v) int hash_v = HashFunc(k) HashTableEntry* p = NULL HashTableEntry* en = ht[hash_v] while (en!= NULL) p = en en= en->n if (en == NULL) en = new HashTableEntry(k, v) if (p == NULL) ht[hash_v] = en else p->n= en else en->v = v End.
For delete:
Begin Declare Function Remove(int k) int hash_v = HashFunc(k) HashTableEntry* en = ht[hash_v] HashTableEntry* p= NULL if (en == NULL or en->k != k) Print “No Element found at key” return while (en->n != NULL) p = en en = en->n if (p != NULL) p->n = en->n delete en Print “Element Deleted” End.
For Search a key value:
Begin Declare function SearchKey(int k) int hash_v = HashFunc(k) bool flag = false HashTableEntry* en = ht[hash_v] if (en != NULL) while (en != NULL) if (en->k == k) flag = true if (flag) Print “Element found at key” Print en->v en = en->n if (!flag) Print “No Element found at key” End.
Example Code
#include <iostream>
const int T_S = 200;
using namespace std;
struct HashTableEntry {
int v, k;
HashTableEntry *n;
HashTableEntry *p;
HashTableEntry(int k, int v) {
this->k = k;
this->v = v;
this->n = NULL;
}
};
class HashMapTable {
public:
HashTableEntry **ht, **top;
HashMapTable() {
ht = new HashTableEntry*[T_S];
for (int i = 0; i < T_S; i++)
ht[i] = NULL;
}
int HashFunc(int key) {
return key % T_S;
}
void Insert(int k, int v) {
int hash_v = HashFunc(k);
HashTableEntry* p = NULL;
HashTableEntry* en = ht[hash_v];
while (en!= NULL) {
p = en;
en = en->n;
}
if (en == NULL) {
en = new HashTableEntry(k, v);
if (p == NULL) {
ht[hash_v] = en;
} else {
p->n = en;
}
} else {
en->v = v;
}
}
void Remove(int k) {
int hash_v = HashFunc(k);
HashTableEntry* en = ht[hash_v];
HashTableEntry* p = NULL;
if (en == NULL || en->k != k) {
cout<<"No Element found at key "<<k<<endl;
return;
}
while (en->n != NULL) {
p = en;
en = en->n;
}
if (p != NULL) {
p->n = en->n;
}
delete en;
cout<<"Element Deleted"<<endl;
}
void SearchKey(int k) {
int hash_v = HashFunc(k);
bool flag = false;
HashTableEntry* en = ht[hash_v];
if (en != NULL) {
while (en != NULL) {
if (en->k == k) {
flag = true;
}
if (flag) {
cout<<"Element found at key "<<k<<": ";
cout<<en->v<<endl;
}
en = en->n;
}
}
if (!flag)
cout<<"No Element found at key "<<k<<endl;
}
~HashMapTable() {
delete [] ht;
}
};
int main() {
HashMapTable hash;
int k, v;
int c;
while (1) {
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>>c;
switch(c) {
case 1:
cout<<"Enter element to be inserted: ";
cin>>v;
cout<<"Enter key at which element to be inserted: ";
cin>>k;
hash.Insert(k, v);
break;
case 2:
cout<<"Enter key of the element to be searched: ";
cin>>k;
hash.SearchKey(k);
break;
case 3:
cout<<"Enter key of the element to be deleted: ";
cin>>k;
hash.Remove(k);
break;
case 4:
exit(1);
default:
cout<<"\nEnter correct option\n";
}
}
return 0;
}Output
1.Insert element into the table 2.Search element from the key 3.Delete element at a key 4.Exit Enter your choice: 1 Enter element to be inserted: 2 Enter key at which element to be inserted: 1 1.Insert element into the table 2.Search element from the key 3.Delete element at a key 4.Exit Enter your choice: 1 Enter element to be inserted: 3 Enter key at which element to be inserted: 4 1.Insert element into the table 2.Search element from the key 3.Delete element at a key 4.Exit Enter your choice: 1 Enter element to be inserted: 7 Enter key at which element to be inserted: 6 1.Insert element into the table 2.Search element from the key 3.Delete element at a key 4.Exit Enter your choice: 1 Enter element to be inserted: 8 Enter key at which element to be inserted: 9 1.Insert element into the table 2.Search element from the key 3.Delete element at a key 4.Exit Enter your choice: 2 Enter key of the element to be searched: 6 Element found at key 6: 7 1.Insert element into the table 2.Search element from the key 3.Delete element at a key 4.Exit Enter your choice: 2 Enter key of the element to be searched: 7 No Element found at key 7 1.Insert element into the table 2.Search element from the key 3.Delete element at a key 4.Exit Enter your choice: 3 Enter key of the element to be deleted: 9 Element Deleted 1.Insert element into the table 2.Search element from the key 3.Delete element at a key 4.Exit Enter your choice: 4
Updated on: 30-Jul-2019
3K+ Views
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