Closest Binary Search Tree Value

给一个 bst和一个double, 问你能不能找到一个值,和target的值最相近.

很naive的解法.在二叉遍历的同时, 记录当前节点值合给的值的差.

public int closestValue(TreeNode root, double target) {
        int res = root.val;
        while(root != null){
            if(Math.abs(root.val - target) < Math.abs(res - target))
                res = root.val;
            if(root.val < target)
                root = root.right;
            else
                root = root.left;
        }
        return res;
}