Win a copy of Think Java: How to Think Like a Computer Scientist this week in the Java in General forum!

need help with binary search tree

jack web
Greenhorn
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
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.

Stephan van Hulst
Bartender
Posts: 5790
61
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
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
Posts: 48917
58
This question is too difficult for "beginning", so I shall move it.

jack web
Greenhorn
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
Posts: 5790
61
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: