calculate the height of binary tree with a given node

[by123]

Hi, how to write a recursive function that takes as input a pointer to the root of the tree and a node, and returns the height of the tree or subtree having the node with the given node as its root.

[D80DSL3A]

That was an interesting problem. I came up with a method which appears to work.
Here's an outline:

Let the start node be pNode, then (in main):

int hMax = 0;
tree.climb(pNode, 0, hMax);
cout << "height of tree = " << hMax;

Where (in the tree class):
int climb(BinNode* pNode, int h, int& hMax);

1) Within the climb function climb to a local treetop from the starting node.

// climb as high as possible
if( pNode->pLeft )	
	h = climb( pNode->pLeft, h+1, hMax );// recursive call
if( pNode->pRight )	
	h = climb( pNode->pRight, h+1, hMax );	

2) When you have reached a top, note your height:

if( h > hMax )
	hMax = h;

3) Then climb back down
return h-1;// climb back down

I'd give the function outright but we're not supposed to give solutions to homework problems here. Hope this helps (and that it actually works under rigorously testing!)