Program to build a binary search tree from an array

 

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

struct node
{
    struct node *left ;
    char data ;
    struct node *right ;
} ;

struct node * buildtree ( int ) ;
void inorder ( struct node * ) ;

char a[ ] = {
            'A', 'B', 'C', 'D', 'E', 'F', 'G', '\0', '\0', 'H', '\0',
            '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0'
            } ;

void main( )
{
    struct node *root ;

    clrscr( ) ;

    root = buildtree ( 0 ) ;
    printf ( "In-order Traversal:\n" ) ;
    inorder ( root ) ;

    getch( ) ;
}
struct node * buildtree ( int n )
{
    struct node *temp = NULL ;
    if ( a[n] != '\0' )
    {
        temp = ( struct node * ) malloc ( sizeof ( struct node ) ) ;
        temp -> left = buildtree ( 2 * n + 1 ) ;
        temp -> data = a[n] ;
        temp -> right = buildtree ( 2 * n + 2 ) ;
    }
    return temp ;
}

void inorder ( struct node *root )
{
    if ( root != NULL )
    {
        inorder ( root -> left ) ;
        printf ( "%c\t", root -> data ) ;
        inorder ( root -> right ) ;
    }
}