Given the insertion order of nodes in a binary search tree, find the distance between two nodes in the tree

DistanceBetweenTwoNodesWithUnbuiltTree.java

import java.util.*;

public class DistanceBetweenTwoNodesWithUnbuiltTree {
	
	/*
	 * Distance between two nodes is number of edges between the two nodes
	 */
	public static int distanceBetweenTwoNodesofBstWithUnbuiltTree(int[] insertionOrder, int node1, int node2) {
		if (insertionOrder == null || insertionOrder.length == 0) {
			return -1;
		}
		
		List<Integer> node1Path = rootToNodeHelper(insertionOrder, node1);
		List<Integer> node2Path = rootToNodeHelper(insertionOrder, node2);
		if (node1Path == null || node2Path == null) {
			return -1;
		}
		
		int node1Runner = 0;
		int node2Runner = 0;
		int node1PathLength = node1Path.size();
		int node2PathLength = node2Path.size();
		while(node1Runner < node1PathLength && node2Runner < node2PathLength && node1Path.get(node1Runner) == node2Path.get(node2Runner)) {
			node1Runner++;
			node2Runner++;
		}
		if (node1Runner == node1PathLength && node2Runner == node2PathLength) {
			// Same nodes
			return 0;
		} else if (node1Runner == node1PathLength) {
			return node2PathLength - node2Runner;
		} else if (node2Runner == node2PathLength) {
			return node1PathLength - node1Runner;
		} else {
			return (node1PathLength - node1Runner) + (node2PathLength - node2Runner);
		}
	}
	
	private static List<Integer> rootToNodeHelper(int[] insertionOrder, int node) {
		int rangeMin = Integer.MIN_VALUE;
		int rangeMax = Integer.MAX_VALUE;
		List<Integer> nodePath = new ArrayList<Integer>();
		for (int i = 0; i < insertionOrder.length; i++) {
			int current = insertionOrder[i];
			if (current < rangeMin || current > rangeMax) {
				continue;
			}
			if (current > node && current < rangeMax) {
				rangeMax = current;
				nodePath.add(current);
			} else if (current < node && current > rangeMin) {
				rangeMin = current;
				nodePath.add(current);
			} else if (current == node) {
				nodePath.add(current);
				break;
			}
		}
		return (nodePath.get(nodePath.size()-1) == node) ? nodePath : null;
	}

	public static void main(String[] args) {
		int[] insertionOrder = {9,1,5,7,8,10,12,4,6};
		System.out.println(distanceBetweenTwoNodesofBstWithUnbuiltTree(insertionOrder, 4, 6));
	}
}