## Title Description

Given a binary search tree, please find the first k smaller nodes therein. For example, (5,3,7,2,4,6,8), the numerical values according to the third junction point is 4 summary.

## Problem-solving ideas

`二叉搜索树按照中序遍历的顺序打印出来正好就是排序好的顺序。`

`所以，按照中序遍历顺序找到第k个结点就是结果。`

## code show as below

```
int index = 0; // counter
the TreeNode KthNode (the root the TreeNode, int k)
{
IF (! the root = null ) { // preorder find the k-th
the TreeNode Node = KthNode (root.left, k);
IF (Node ! = null )
return Node;
index ++ ;
IF (index == K)
return the root;
Node = KthNode (root.right, K);
if(node != null)
return node;
}
return null;
}
```