Two nodes of a binary search tree have been incorrectly swapped. How will you efficiently restore the tree to its correct state?

An inorder traversal of BST will be in sorted order.

In the incorrect BST  2 of the nodes are swapped .

use this to your advantage and find these 2 elements in inorder traversal which violate the sorted order.This 2 elements need to  be swapped.Thats it!!

Just modify inorder traversal function as follows

[gist https://gist.github.com/vishnujayvel/5879942 ]

Printing nodes at the K distance from root of a binary Tree

Here is a recursive solution.The code is self explanatory

[gist https://gist.github.com/vishnujayvel/5871650]

Printing nodes at the K distance from root of a binary Tree

Here is a recursive solution.The code is self explanatory

[gist https://gist.github.com/vishnujayvel/5871650]