235-Lowest-Common-Ancestor-of-a-Binary-Search-Tree.scala

/**
 * Definition for a binary tree node.
 * class TreeNode(var _value: Int) {
 *   var value: Int = _value
 *   var left: TreeNode = null
 *   var right: TreeNode = null
 * }
 */

import annotation.tailrec

object Solution {
    @tailrec
    def lowestCommonAncestor(root: TreeNode, p: TreeNode, q: TreeNode): TreeNode = {
        if (p.value < root.value && q.value < root.value) {
            lowestCommonAncestor(root.left, p, q)
        } else if (p.value > root.value && q.value > root.value) {
            lowestCommonAncestor(root.right, p, q)
        } else {
            root
        }
    }
}