题解 | #二叉搜索树第k小节点#

根据二叉搜索的性质可知，中序遍历即位从小到大顺序，可以使用中序遍历将其存起来取出目标节点，也可直接中序遍历同时得到节点

/*
public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

    public TreeNode(int val) {
        this.val = val;

    }

}
*/
public class Solution {
    int index = 0;
    TreeNode res = null;
    TreeNode KthNode(TreeNode pRoot, int k) {
        if(pRoot==null||k == 0){
        return null;
        }
        KthNode(pRoot.left,k);
        index++;
        if(index == k){
        res = pRoot;
        }
        KthNode(pRoot.right,k);
        return res;
    }
}