The nearest common ancestor of 235 binary search tree

subject ：

Their thinking ： recursive , Two points of binary search tree

Binary search tree ： Binary search tree , The main features are , The root node is larger than the left child , Younger than the right child , In the middle of the left small right big root .

/**
 * Definition for a binary tree node.
 * function TreeNode(val) {
 *     this.val = val;
 *     this.left = this.right = null;
 * }
 */
/**
 * @param {TreeNode} root
 * @param {TreeNode} p
 * @param {TreeNode} q
 * @return {TreeNode}
 */
var lowestCommonAncestor = function(root, p, q) {
    var res;
    result(root, p, q);

    function result(root, p, q) {
        if ((root.val - p.val) * (root.val - q.val) <=0) {
            res = root
        } else if (root.val < p.val && root.val < q.val) {
            result(root.right, p, q)
        } else result(root.left, p, q)
    }

    return res;
};

Of course, the original idea is not mine , This is easier to understand .

notes ： Pay attention to the second special case , So in the first one if Processing in judgment .

My initial idea was to do two iterations , It is troublesome and difficult to understand , But it can also ac.（ps: The first day ）