DSA_A1.cpp

/*A1-Consider telephone book database of N clients. Make use of a hash table implementation
to quickly look up client‘s telephone number. Make useof two collision handling techniques
and compare them using number of comparisons required to find a set
of telephone numbers*/


# include <iostream>
# include<string.h>
using namespace std ;

struct node{
    int value;
    node* next;
};

class hashing{
    public:
    node* HashTable[10];
    hashing(){
        for (int i=0 ; i<10 ; i++){
            HashTable[i]=NULL;

        }
    }

    int HashFunction(int value ){
        return(value%10);

    }

    node* create_node(int x){
        node* temp = new node;
        temp->next = NULL;
        temp-> value = x;
        return temp;
    }

    void display(){
        for (int i=0 ; i<10 ; i++){
            node*temp = new node;
            temp = HashTable[i];
            cout<<"a["<<i<<"]:";
            while(temp != NULL){
                cout<<"->"<<temp->value;
                temp=temp->next;
            }
            cout<<"\n";

        }
    }

    int searchElement(int value){
        bool flag = false;
        int hash_val= HashFunction(value);
        node* entry = HashTable[hash_val];
        cout<<"\nElement found at: ";
        while(entry != NULL){
            if (entry-> value == value){
                cout<<hash_val<<":"<<entry->value<<endl;
                flag=true;

            }
            entry=entry->next;
        }
        if (!flag)
            return -1;
    }

    void deleteElement(int value){
        int hash_val=HashFunction(value);
        node* entry = HashTable[hash_val];
        if (entry == NULL ){
            cout<<"no element found";
            return;
        }

        if(entry->value==value){
            HashTable[hash_val]=entry->next;
            return ; 
        }
        while((entry->next)->value != value){
            entry = entry->next;
        }
        entry->next = (entry->next)->next;

    }

    void insertElement(int value){
        int hash_val= HashFunction(value);
        //node*prev = NULL;
        //node*entry = HashTable[hash-val];
        node*temp = new node;
        node* head = new node;
        head = create_node(value);
        temp = HashTable[hash_val];

        if (temp==NULL){
            HashTable[hash_val]=head;
        }
        else{
            while(temp->next != NULL){
                temp = temp->next;

            }
            temp->next= head;
        }

    }


};


int main(){
    int ch;
    int data;
    int search,del;
    hashing h;
    do{
        //fflush(stdin);
        cout<<"\nTelephone : \n1.insert \n2.display \n3.search \n4.delete \n5.exit"<< endl;
        cout<<"Enter your choice : "<<endl; 
        cin>>ch;
        switch(ch){
            case 1:cout<<"\nEnter phone no. to be inserted : ";
                cin>>data;
                h.insertElement(data);
                break;

            case 2:h.display();
                break;

            case 3:cout<<"\nEnter the no to be searched : ";
                cin>>search;
                if (h.searchElement(search)==-1){
                    cout<<"No element found at key ";
                    continue;
                }
                break;

            case 4:cout<<"\nEnter the phno. to be deleted : ";
                cin>>del;
                h.deleteElement(del);
                cout<<"phno. deleted"<<endl;
                break;

            default :cout<<"invalid case"<<endl;
                break;

        }
    }while(ch!= 5);

    return 0;


}