235. Lowest Common Ancestor of a Binary Search Tree

两个数都小于根节点，都位于左子树，都大于都位于右子树。一大一小就是根节点。递归实现

public class Solution {

    //2, 1

    public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {

        if(Math.max(p.val, q.val) < root.val) {

            return lowestCommonAncestor(root.left, p, q);

        } else if(Math.min(p.val, q.val) > root.val) {

            return lowestCommonAncestor(root.right, p, q);

        } else return root;

    }

}