bst

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <string.h>

typedef struct _node
{
  int key;
  struct _node *left, *right;
} node;

void insert(node** at, node* elem)
{
  assert(elem);

  if(!*at)
  {
    *at = elem;
  }
  else if(elem->key < (*at)->key)
  {
    insert(&(*at)->left, elem);
  }
  else
  {
    insert(&(*at)->right, elem);
  }
}

void print_tree(node* at)
{
  static int i = 0;
  int k;

  if(!at)
  {
      return;
  }
  else
  {
      i++;
  }

  print_tree(at->right);

  for(k = 0; k < i; k++)
  {
      printf("  ");
  }
  printf("%d\n", at->key);

  print_tree(at->left);

  i--;
}

int main()
{
  int i, n;
  node *root = NULL, *np = NULL;

  scanf("%d", &n);

  for(i = 0; i < n; i++)
  {
    np = (node*)malloc(sizeof(node));
    memset(np, 0, sizeof(node));
    scanf("%d", &np->key);
    insert(&root, np);
  }

  printf("\n");
  print_tree(root);
  printf("\n");

  return 0;
}