Lowest Common Ancestor of a Binary Search Tree [LC#235]

Given a binary search tree (BST), find the lowest common ancestor (LCA) node of two given nodes in the BST. According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between two nodes p and q as the lowest node in T that has both p and q as descendants (where we allow a node to be a descendant of itself).”

Time complexity

$T(n) = O(n)$ and $S(n)= O(n)$ for the recursion stack in worst case.