I was trying to solve this problem.

Problem Statement

You are given a pointer to the root of a binary tree. Print the top view of the binary tree. You only have to complete the function.

For example :

     3
   /   \
  5     2
 / \   / \
1   4 6   7
 \       /
  9     8
Top View : 1 -> 5 -> 3 -> 2 -> 7

I figured that the answer could be obtained by keeping on going till the leftmost node recursively and then traverse the tree till the rightmost node from the root.

Although I have managed to solve this problem I feel that my solution is just a little hack and not the best possible solution. The function I had written is

/*
struct node
{
    int data;
    node* left;
    node* right;
};

*/
void top_view(node * root)
{
   static node* temp = root;
   if(root == NULL)
    {
    return;
   }
   top_view(root->left);
   cout<<root->data<<" ";
   if(root == temp)
      {
      root = root->right;//Don't want to print the root element twice
      while(root != NULL)
         {
         cout<<root->data<<" ";
         root = root->right;
      }
   } 
}