/* Program to demonstrate hashing using modulo division and linear probing */

#include  <stdio.h>
#include  <conio.h>
#define  size  10

/* The hashtable size is normally 5 times the size of original array. However, in this program I have  taken the size of hashtable same as original array */
int  ht[size] ;

void  store(int  x[ ], int  n) ;
int  modulodivision(int  key) ;
int  linearprobe(int  address) ;
void  hashsearch() ;

void main()
{
    int  i, n, x[10] ;
    char  ch ;
    clrscr() ;
    printf("Enter the number of elements: ") ;
    scanf("%d",&n) ;
    printf("Enter the elements:\n") ;
    for(i=0 ; i<n ; i++)
        scanf("%d",&x[i]) ;
    store(x,n) ;
    printf("Hashtable is as shown:\n") ;
    for(i=0 ; i<size ; i++)
        printf("%d ", ht[i]) ;
    printf("\n") ;
    do
        {
            hashsearch() ;
            printf("Do you want to search another element ? ") ;
            flushall() ;
            scanf("%c",&ch) ;
        }
    while(ch=='y'||ch=='Y') ;
    getch() ;
}

void  store(int  x[ ], int  n)
{
    int  i, key, address ;
    /* Initializing hash table to empty */
    for(i=0 ; i<size ; i++)
        ht[i]=-1 ;
    /* Copying elements from original array to hashtable */
    for(i=0 ; i<n ; i++)
        {
            key=x[i] ;
            address=modulodivision(key) ;
            if(ht[address]!=-1)
                address=linearprobe(address) ;
            ht[address]=key ;
        }
}

/* Hash Function */
int  modulodivision(int  key)
{
    int  address ;
    address=key%size+1 ;
    if(address==size)
        return  0 ;
    else
        return  address ;
}

/* Collision Resolution */
int  linearprobe(int  address)
{
    while(ht[address]!=-1)
        {
            address++ ;
            if(address==size)
                address=0 ;
        }
    return  address ;
}

/* Searching in hashtable */
void  hashsearch()
{
    int  key, address ;
    printf("Enter the element to be searched: ") ;
    scanf("%d",&key) ;
    address=modulodivision(key) ;
    while(ht[address]!=key && ht[address]!=-1)
        {
            address++ ;
            if(address==size)
                address=0 ;
        }
    if(ht[address]==-1)
        printf("%d not found \n",key) ;
    else
        printf("%d found at position %d \n",key,address) ;
}