/* Program to demonstrate recursive binary search */

/* We assume that the array is sorted in ascending order */

#include  <stdio.h>
#include  <conio.h>

int  binary(int  x[ ], int  low, int  high, int  key) ;

void  main()
{
    int  i, n, x[20], key ;
    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]) ;
    printf("Enter the element to be searched: ") ;
    scanf("%d",&key) ;
    i=binary(x,0,n-1,key) ;
    if(i==-1)
        printf("%d not found.", key) ;
    else
        printf("%d found at position %d.", key,i) ;
    getch() ;
}

int  binary(int  x[ ], int  low, int  high, int  key)
{
    int  mid ;
    if(low>high)
        return  -1 ;
    mid=(low+high)/2 ;
    if(key==x[mid])
        return mid ;
    else if(key<x[mid])
        return (binary(x,low,mid-1,key)) ;
    else
        return (binary(x,mid+1,high,key)) ;
}
/* The condition (key<x[mid]) will become (key>x[mid]) if array x is in descending order */