Binary Tree using linked list with preorder traversal.

Code:-
#include<stdio.h>




typedef struct node


{


    int data;


    struct node *left;


    struct node *right;


}node;




node *create()


{


    node *p;


    int x;


    printf("Enter data(-1 for no data):");


    scanf("%d",&x);




    if(x==-1)
return NULL;




    p=(node*)malloc(sizeof(node));


    p->data=x;




    printf("Enter left child of %d:\n",x);


    p->left=create();


    printf("Enter right child of %d:\n",x);


    p->right=create();




    return p;


}




void preorder(node *t)              //address of root node is passed in t


{


    if(t!=NULL)


    {
printf("\n%d",t->data);  
//visit the root
preorder(t->left);          //preorder traversal on left subtree
preorder(t->right);         //preorder traversal om right subtree
}


}




int main()


{


    node *root;


    root=create();




    printf("\nThe preorder traversal of tree is:\n");


    preorder(root);


    return 0;


}



Output:-
Enter data(-1 for no data):5
Enter left child of 5:
Enter data(-1 for no data):8
Enter left child of 8:
Enter data(-1 for no data):-1
Enter right child of 8:
Enter data(-1 for no data):-1
Enter right child of 5:
Enter data(-1 for no data):9
Enter left child of 9:
Enter data(-1 for no data):-1
Enter right child of 9:
Enter data(-1 for no data):-1

The preorder traversal of tree is:

5
8
9