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need help with binary search tree

jack web
Greenhorn

Joined: Mar 13, 2011
Posts: 5
I just started programming in general and started with Java, in an assignment I got I need to find the longest increasing path of a binary search tree of integer. however I have no idea how to carry it out. I know how to count the longest path of a binary search tree, just not when you need to find the path that's the longest with the values increasing.

the part I am stuck with is that my code only counts the longest path of the right of the root node
Wouter Oet
Saloon Keeper

Joined: Oct 25, 2008
Posts: 2700

With your solution do you keep the following tree in mind:


You need something to define what a path in a tree is. You could keep track of the nodes or the start and end node.


"Any fool can write code that a computer can understand. Good programmers write code that humans can understand." --- Martin Fowler
Please correct my English.
Stephan van Hulst
Bartender

Joined: Sep 20, 2010
Posts: 3649
    
  17

Jack, do you have a binary search tree, or just a simple binary tree?

If the former, then the longest increasing path would simply be the path from the root to the rightmost leaf.

However, if it's not a search tree, then you will have to call the method recursively on both subtrees.
jack web
Greenhorn

Joined: Mar 13, 2011
Posts: 5
Stephan van Hulst wrote:Jack, do you have a binary search tree, or just a simple binary tree?

If the former, then the longest increasing path would simply be the path from the root to the rightmost leaf.

However, if it's not a search tree, then you will have to call the method recursively on both subtrees.


I am guessing it would be just a binary tree, with what i wrote i cant really figure out how to solve a method in case of


in this case the longest should be 3 (with 5->7->8->9) but my code will return 2 (with 10->12->13)
Campbell Ritchie
Sheriff

Joined: Oct 13, 2005
Posts: 39869
    
  28
This question is too difficult for "beginning", so I shall move it.
jack web
Greenhorn

Joined: Mar 13, 2011
Posts: 5
out of curiosity what is the cost of find the leaves in a binary tree in big O notation
Stephan van Hulst
Bartender

Joined: Sep 20, 2010
Posts: 3649
    
  17

Here's a tip:

For any binary tree, the length of the longest increasing path would be the length of the longest increasing path of either the left subtree, or the right subtree, whichever is bigger, plus 1 if the path starts at the root of the subtree, and the root of the parent is smaller than the root of the subtree.

Here are some helper method you could use:
Slayers Zelgadis
Greenhorn

Joined: Jun 14, 2011
Posts: 1
Done!
 
 
subject: need help with binary search tree