Optimization to improve the time and space complexity

[tyagi85prashant]

change1:-
Using HashSet (look-up is O(1)) for pathRenderedCache which is optimized compared ArrayList

change 2:-
Calculation of leaf span
Using recursion to optimize the method by reducing the number of object created

[decebals]

Just a curiosity. It's clear that this method is better then getLeafs(node).size(). Another possible implementation is similar with getLeafs(node) but with a variable leafsSize instead of leafs:

public static List<Node> getLeafs(Node root) {
	List<Node> leafs = new ArrayList<Node>();
	Iterator<Node> it = new TreeIterator(root);
	while (it.hasNext()) {
		Node node = it.next();
		if (node.isLeaf()) {
			leafs.add(node);
		}
	}
		
	return leafs;
}

public static List<Node> getLeafsSize(Node root) {
	int leafsSize = 0;
	Iterator<Node> it = new TreeIterator(root);
	while (it.hasNext()) {
		Node node = it.next();
		if (node.isLeaf()) {
			leafsSize++;
		}
	}
		
	return leafsSize;
}

In this mode I eliminate the recursive call.

[tyagi85prashant]

i agree,this will work as well

[decebals]

Thanks! I love to see code that optimize something but I must admit that are rare the moments when something submit code that resolve a performance problem.

[rototor]

Did you do any benchmarks? How much improvement is gained with this patch?