I was working on Binary Search trees and my concept on recursion is not the best that it can be. So I chose to use recursion to do all the basic tasks. The only problem that was having was with my display function. I can print out all the nodes with their respective root nodes but instead of it printing on the same line, it prints it on multiple lines. Output:

I've tried using if else statements to to call the left and right subtrees when not null but I still get the same output.

node_tree *display(node_tree *ref, int spaces){
        if (ref==NULL)
           return ref; 

        spaces = spaces/2; 
        for(int j = 0 ; j< spaces; j++)
         printf(" "); 
        printf("%d\n", ref->data);
        //display(ref->left, spaces); 
        //printf("%d", ref->data);
        //display(ref->right, spaces);new after this line
        if (ref->left!=NULL&&ref->right!=NULL){
          display(ref->right, 3*spaces); display(ref->left, spaces);
        else if(ref->right ==NULL){
          display(ref->left, spaces);
        else if(ref->left ==NULL){
          display(ref->right, 3*spaces);

        //printf("%d\n", ref->data); 



Expected Output

    10    13
  9  11
  • spaces was passed from the main function with value as total nodes present in the tree. – Yathartha Oct 19 at 19:51
  • You might have to do a level order traversal for your requirement. This is working because right child does (13) not have further child. – CaffeinatedCod3r Oct 19 at 19:58

if left internal node have two specific external nodes and with in-order traversal; you can try it like:

int  node_height(node* node)
    int u, v;

    if (node == NULL)
        return -1;

    u = node_height(node->left);
    v = node_height(node->right);

    if (u > v)
        return u + 1;
        return v + 1;

void node_print(char* ch, int height)
    int i;

    for (i = 0; i < height; i++)
        printf(" ");

    printf("%c", ch);

void node_show(node* node, int height)

    if (node == NULL) {
        node_print('*', node_height(node));


    node_show(node->right, node_height(node) + 1);
    node_print(node->item, node_height(node));
    node_show(node->left, node_height(node) + 1);

call the node_show(node, node_height(node)) function with given height.

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