235. Lowest Common Ancestor of a Binary Search Tree

    /*
     * 235. Lowest Common Ancestor of a Binary Search Tree 
     * 2016-6-15 By Mingyang
     * 这题目更简单，下面两种方法都适用，现在给出更直接的方法
     */
    public TreeNode lowestCommonAncestor3(TreeNode root, TreeNode p, TreeNode q) {
        if (p.val == root.val || q.val == root.val)
            return root;
        if ((p.val < root.val && q.val > root.val)|| (p.val > root.val && q.val < root.val))
            return root;
        if (p.val < root.val) {
            return lowestCommonAncestor(root.left, p, q);
        } else {
            return lowestCommonAncestor(root.right, p, q);
        }
    }