/**
 * Definition for a binary tree node.
 * class TreeNode(var `val`: Int = 0) {
 *     var left: TreeNode? = null
 *     var right: TreeNode? = null
 * }
 */

class Solution {
    fun lowestCommonAncestor(root: TreeNode?, p: TreeNode?, q: TreeNode?): TreeNode? {
        var ancestor: TreeNode? = null
        var pTrack = root
        var qTrack = root

        while (pTrack == qTrack && pTrack != null && qTrack != null) {
            ancestor = pTrack

            if (pTrack!!.`val` == p!!.`val`) {
                return p
            } else if (p!!.`val` < pTrack!!.`val`) {
                pTrack = pTrack.left
            } else {
                pTrack = pTrack.right
            }

            if (qTrack!!.`val` == q!!.`val`) {
                return q
            } else if (q!!.`val` < qTrack!!.`val`) {
                qTrack = qTrack.left
            } else {
                qTrack = qTrack.right
            }
        }

        return ancestor
    }
}